Module for in-line recharging of sorbent materials with optional bypass

ABSTRACT

A module for optionally recharging sorbent materials in-line, including zirconium phosphate, with an optional bypass and conduits for a sorbent cartridge. The sorbent cartridge can have one or more modules contained therein having connectors connecting each of the modules. One or more of the modules can be reusable and the sorbent materials therein recharged.

FIELD OF THE INVENTION

The invention relates to modules for optional in-line recharging ofsorbent materials in a sorbent cartridge. The modules can be detachable,and the sorbent materials can include zirconium phosphate.

BACKGROUND

Dialysis involves the movement of blood through a dialyzer that has asemi-permeable membrane. Simultaneously, dialysate is circulated throughthe dialyzer on an opposite side of the semi-permeable membrane. Toxinspresent in the blood stream of the patient pass from the blood throughthe membrane into the dialysate. After passing through the dialyzer, thespent dialysate is discarded. Disposal of spent dialysate requires alarge amount of source water for preparing the replacement dialysatenecessary for use during continuous dialysis. However, in sorbentdialysis systems, the spent dialysate is re-circulated through a sorbentcartridge rather than being discarded. The sorbent cartridge containslayers of sorbent material which selectively remove specific toxins, orbreak down toxins, in the dialysate.

The advantage of sorbent dialysis is that a much lower amount of wateris required. In four hours of traditional dialysis, up to 120 L of watermay be required to generate the dialysate. By contrast, using sorbentdialysis, as little as 6 or 7 L of water may be necessary. Thus, theneed for drains and a continuous source of purified water areeliminated, rendering the system portable.

One of the drawbacks of sorbent dialysis systems is the high cost. Thematerials used in the sorbent cartridges can be expensive. Disposing ofthe cartridges after each use generates waste and drives up costs. Otherknown dialysate fluid circulation systems and apparatuses have separatehousings where a first housing has a material capable of releasingsodium into dialysate fluid flowing through the first housing, and asecond housing has a material capable of binding sodium ions fromdialysate fluid flowing through the second housing. However, suchsystems cannot be formed into a single housing design, oftentimesrequire many liters of water, and may not be portable. The systems alsodo not provide for recharging some or all of the components of a sorbentcartridge that would allow reuse of specific components and enable lowerlong-term costs for operating such systems.

Hence, there is a need for a sorbent cartridge having a separation ofmaterials within the sorbent cartridge into modules to allow forisolation of those materials. There is a need for a sorbent cartridgeproviding for isolation of one or more sorbent materials to allow forcheaper or non-reusable materials to be discarded, while more expensiveand reusable materials are recharged. There is a further need for aunitary sorbent cartridge having multiple discreet modules that can beeasily connected and/or detached from the unitary sorbent cartridgethereby facilitating the recharging and/or recycling of the sorbentmaterials and the sorbent cartridge while retaining a single unitarydesign. There is also a need for a modular sorbent cartridge having thefeatures of reduced size and weight necessary for a portable dialysismachine. There is a need for a modular sorbent cartridge wherein thesorbent materials can be arranged within the modules of the cartridge toallow for isolation of particular materials or groups of materials.There is further a need for any one of the modules in the cartridge tobe reusable or optionally detachable from the cartridge to allow any oneof disposal, recycling or recharging of sorbent material within themodule. There is a need for a sorbent cartridge having specificmaterials that can be recharged and allowing for disposal of lessexpensive materials.

There is a need for the sorbent materials to be recharged withoutremoving the modules from the sorbent cartridge during operation, makingthe system easier to use. There is a need for a recharging meansdirectly attached to the sorbent modules, to allow the modules to berecharged simply by directing fluid flow from the rechargers to themodule. There is further a need for one or more of the modules to beremovable to allow for the recycling and/or disposal of these modules,while allowing for the recharging of other modules.

SUMMARY OF THE INVENTION

The present invention relates to a sorbent cartridge comprising at leastone reusable module. In any embodiment, the sorbent cartridge can haveone or more reusable modules having one or more connectors fluidlyconnectable to any part of a fluid flow path selected from any one of awash line, a fluid line, or a bypass line. In any embodiment, the washline can optionally be fluidly connectable to a recharger, and thebypass line can optionally be fluidly connectable to another module.Moreover, the fluid line can be optionally fluidly connectable to anyportion of a dialysis circuit.

In one embodiment, at least one valve can be positioned before and/orafter the modules on the connectors to selectively direct flow throughat least one module, wash line, recharger, and/or bypass line. The flowcan be comprised of either gas or liquid.

In any embodiment, the sorbent cartridge can have one or more modulesthat make up the sorbent cartridge. The one or more detachablecartridges can be reusable or non-reusable.

In another embodiment, any one of four-way, three-way, two-way valves,or combinations thereof, can be positioned before and/or after themodules on the connectors to selectively direct flow through themodules, wash line, recharger, or bypass line.

In another embodiment, the sorbent cartridge can be configured so thatthe reusable module is in an off-line state by being fluidly connectableto a recharger. In yet another embodiment, the reusable module can beconfigured to be in an in-line state by being fluidly connectable to anyone of the fluid line or the bypass line.

In other embodiments, a first module, which can be a reusable module,and the second module can be connected in series. A first bypass linecan connect a first valve, positioned on a connector before the firstmodule, to a second valve. A second bypass line can connect the secondvalve to a third valve positioned on a connector between the first andsecond module. A third bypass line can connect the second valve and afourth valve positioned on a connector after the second module.

In another embodiment, the first module, which can be a reusable module,and the second module can be connected in series such that a first valvecan be positioned on a connector before the first module, and canconnect a bypass line to a second valve positioned on a connectorbetween the first and second modules. The bypass line can furtherconnect to a third valve positioned on a connector after the secondmodule.

In another embodiment, the first module, which can be a reusable module,and the second module can be connected in series, and a first bypassline can connect a first valve, positioned on a connector before thefirst module, to a second valve positioned on a connector between thefirst and second modules. A second bypass line can connect a thirdvalve, positioned on the connector between the first and second module,to a fourth valve positioned on a connector after the second module.

In another embodiment, a first module, which can be a reusable module,and the second module can be connected in series, and a first bypassline can connect a first valve positioned on a connector before thefirst module to a second valve positioned on a connector between thefirst module and the second module. A second bypass line can connect athird valve positioned on the connector between the first and secondmodules to a fourth valve positioned on a connector after the secondmodule. A first wash line can connect the first valve to a firstrecharger connector or node, a second wash line can connect the secondvalve to the first recharger connector or node, a third wash line canconnect the third valve to a second recharger connector or node, and afourth wash line can connect the fourth valve to the second rechargerconnector or node.

In another embodiment, a first module, which can be a reusable module,and the second module can be connected in series. A first valvepositioned on a connector before the first module can connect a firstwash line to a first recharger connector. A second wash line can connecta second valve, positioned on a connector between the first and secondmodules, to the first recharger connector; a third wash line can connecta third valve, positioned on the connector between the first and secondmodules, to a second recharger connector; and a fourth wash line canconnect a fourth valve, positioned on a connector after the secondmodule, to the second recharger connector. A fifth valve, positioned onthe connector before the first module, can connect a bypass line to asixth valve positioned on the connector between the first module and thesecond module, and can further connect to a seventh valve positioned onthe connector after the second module.

In another embodiment, the sorbent cartridge can comprise at least onereusable removable module with one or more connectors.

In another embodiment, the sorbent cartridge can comprise at least onenon-reusable module.

In another embodiment, the reusable module can contain sorbent material.

In another embodiment, the reusable module can contain multiple sorbentmaterials.

In another embodiment the non-reusable module can contain sorbentmaterial.

In another embodiment, the non-reusable sorbent module can containmultiple sorbent materials.

In any embodiment, the connectors connecting the modules may be selectedfrom a group comprising quick-connect, twist-lock, push-on and threadedfittings.

In any embodiment, the connectors may comprise a length of tubing and avalve or a valve assembly.

In one embodiment, the at least one reusable module is detachable fromthe sorbent cartridge.

In one embodiment, the reusable module contains sorbent materials thatmay be selected from a group comprising zirconium phosphate, hydrouszirconium oxide, activated carbon, alumina, urease and ion exchangeresin. In any embodiment, the ion-exchange resin can be selected to onlyremove sodium, potassium, calcium and magnesium ions. The ion exchangeresin can also be a chelating ion-exchange resin. The respective layerscan be formed into any combination of layers without restriction.

In one embodiment, the non-reusable module contains sorbent materialsthat may be selected from a group comprising zirconium phosphate,hydrous zirconium oxide, activated carbon, alumina, urease and ionexchange resin. In any embodiment, the ion-exchange resin can beselected to only remove sodium, potassium, calcium and magnesium ions.The ion-exchange resin can also be a chelating ion-exchange resin. Therespective layers can be formed into any combination of layers withoutrestriction.

In one embodiment, the reusable module may be recyclable and/orrechargeable.

In any embodiment, at least one module may have a barcode or otheridentification system.

In any embodiment, the connectors may include an access point for asensor.

The invention also relates to a fluid circuit. In one embodiment, thefluid circuit can have at least two modules connected by one or moreconnectors in series. An operational line can direct flow along theconnectors and through the modules. A wash line can fluidly connect oneor more connectors to a recharger. A bypass line can bypass the modulesand the operational line.

In one embodiment, the bypass line of the fluid circuit can be in fluidcommunication with at least one sorbent material.

The invention also relates to a method of recharging a sorbent. In oneembodiment, the method can include connecting at least a first module,which can be a reusable module, and second module in series with one ormore connectors. At least one connector can be fluidly connected to atleast one wash line, and the at least one wash line can be fluidlyconnected to a recharger. At least one connector can be fluidlyconnected to a bypass line. The bypass line can divert flow from theconnector to bypass at least one module. The method can includeconnecting one or more valves to the connectors at junctions between themodules, wash lines and/or bypass lines. The method can includeselectively opening and closing the valves to direct flow through theconnectors, modules, wash lines and/or bypass lines.

In another embodiment, the method can include a valve positioned on aconnector before a first module, which can be a reusable module. Thevalve can connect the connector, a wash line, and a bypass line. Thevalve can be open to the wash line and closed to the connector and thebypass line such that flow is directed to a recharger.

In another embodiment, the method can include a valve positioned on aconnector before the first module, which can be a reusable module. Thevalve can connect the connector, a wash line, and a bypass line. Thevalve can be open to the wash line and connector and closed to thebypass line such that flow circulates between the first module and therecharger. A second valve can be positioned on a connector between thefirst module and the second module and can be closed such that flowcannot continue from the first module to the second module.

In another embodiment, the method can include a valve positioned on aconnector before the first module, which can be a reusable module. Thevalve can connect the connector, a wash line, and a bypass line. Thevalve can be open to the bypass line and closed to the wash line andconnector, such that flow is directed through the bypass line to bypassthe first module.

In another embodiment, the method includes a valve positioned on aconnector before the first module, which can be a reusable module. Thevalve can connect the connector, a wash line, and a bypass line. Thevalve can be open to the connector and closed to the bypass and washlines, such that flow is directed through the connector and through thefirst module.

In another embodiment, the method can include a pump attached to therecharger or wash line.

In another embodiment a gas, such as argon, air, filtered air, nitrogen,and helium can be used to blow out the module.

In another embodiment the wash lines can be subdivided into a top and abottom wash line.

In another embodiment, the top line can be a fluid line and the bottomline can be a gas line.

In another embodiment, the top line can be a gas line and the bottomline can be a fluid line.

In another embodiment the top and bottom lines can both be fluid lines.

In one embodiment, the at least two modules can be part of a controlledcompliant dialysis circuit.

In one embodiment, the valves can be operated under control of aprogrammable controller or computer system to regulate flow into, outof, and between modules.

In one embodiment, fluid flow through the valves may be sensed by aphotocell or other flow sensing and/or measuring apparatus.

In another embodiment, a control pump can circulate fluid in the flowpath.

In another embodiment, the sorbent materials may be mixed together.

In another embodiment, the sorbent cartridge can have a first module,which can be a reusable module, and a second module connected in series.The first module can be fluidly connected to a first set of one or morevalves positioned on a first set of one or more connectors before thefirst module, such that fluid may be directed into the first module. Abypass line can be fluidly connected to the first set of one or morevalves such that fluid can bypass the first module. A first rechargercan be fluidly connected to the first set of one or more valves suchthat fluid may be directed from the first recharger to the first module.The first module can be fluidly connected to a second set of one or morevalves positioned on a second set of one or more connectors after thefirst module and before the second module, such that fluid may bedirected from the first module into the second module. The bypass linecan be fluidly connected to the second set of one or more valves suchthat fluid can bypass the second module. The first recharger can beconnected to the second set of one or more valves such that fluid may bedirected from the first module to the first recharger. A secondrecharger can be fluidly connected to the second set of one or morevalves such that fluid may be directed from the second recharger to thesecond module. The second recharger can be fluidly connected to a thirdset of one or more connectors positioned after the second module suchthat fluid may be directed from the second module to the secondrecharger.

In another embodiment, the sorbent cartridge can have a first module,which can be a reusable module, and a second module connected in series.The first module can be fluidly connected to a first set of one or morevalves positioned on a first set of one or more connectors before thefirst module, such that fluid may be directed into the first module. Abypass line can be fluidly connected to the first set of one or morevalves such that fluid can bypass the first module. The first module andbypass line can be fluidly connected to a second set of one or morevalves positioned on a second set of one or more connectors after thefirst module and before the second module, such that fluid may bedirected from the first module into the second module. The bypass linecan be fluidly connected to the second set of one or more valves suchthat fluid can bypass the second module.

In another embodiment, the sorbent cartridge can have a first module, asecond module, and a third module connected in series. Any one of themodules can be reusable. The first module can be fluidly connected to afirst set of one or more valves positioned on a first set of one or moreconnectors before the first module, such that fluid may be directed intothe first module. A bypass line can be fluidly connected to the firstset of one or more valves such that fluid can bypass the first module. Afirst recharger can be fluidly connected to the first set of one or morevalves such that fluid may be directed from the first recharger to thefirst module. The first module can be fluidly connected to a second setof one or more valves positioned on a second set of one or moreconnectors after the first module and before the second module, suchthat fluid may be directed from the first module into the second module.The first recharger can be connected to the second set of one or morevalves such that fluid may be directed from the first module to thefirst recharger. The bypass line can be fluidly connected to the secondset of one or more valves such that fluid can bypass the second module.A second recharger can be fluidly connected to the second set of one ormore valves such that fluid may be directed from the second recharger tothe second module. The second module can be fluidly connected to a thirdset of one or more valves positioned on a third set of one or moreconnectors after the second module and before the third module, suchthat fluid may be directed from the second module into the third module.The second recharger can be fluidly connected to the third set of one ormore valves such that fluid from the second module may be directed tothe second recharger. The bypass line can be fluidly connected to thethird set of one or more valves such that fluid can bypass the thirdmodule. A third recharger can be fluidly connected to the third set ofone or more valves such that fluid may be directed from the thirdrecharger to the third module. The third module can be fluidly connectedto a fourth set of one or more connectors. The third recharger can befluidly connected to the fourth set of one or more connectors such thatfluid may be directed from the third module to the third recharger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sorbent cartridge containing activated carbon, hydrouszirconium oxide, urease, alumina, and zirconium phosphate.

FIG. 2 shows a modular sorbent cartridge with two modules.

FIG. 3 shows a modular sorbent cartridge with two modules includingactivated carbon, alumina, urease, and zirconium oxide in the firstmodule, which can be a reusable module, and zirconium phosphate in thesecond module, which can be a reusable module.

FIG. 4 shows a method for recharging the zirconium phosphate sorbentmaterial.

FIG. 5 shows a modular sorbent cartridge with two modules includingactivated carbon, zirconium phosphate, urease, alumina, and hydrouszirconium oxide in the first module, which can be a reusable module, andzirconium phosphate in the second module.

FIG. 6 shows a modular sorbent cartridge with two modules includingactivated carbon, ion exchange resin, alumina, urease, and hydrouszirconium oxide in the first module, which can be a reusable module, andzirconium phosphate in the second module.

FIG. 7 shows a modular sorbent cartridge with two modules includingactivated carbon, alumina, urease, and zirconium phosphate in the firstmodule, which can be a reusable module, and hydrous zirconium oxide andzirconium phosphate in the second module.

FIG. 8 shows a modular sorbent cartridge with two modules includingactivated carbon, alumina, urease, and hydrous zirconium oxide in thefirst module, which can be a reusable module, and ion exchange resin andzirconium phosphate in the second module.

FIG. 9 shows a modular sorbent cartridge with two modules includingactivated carbon, alumina, and urease in the first module, which can bea reusable module, and hydrous zirconium oxide, ion exchange resin, andzirconium phosphate in the second module.

FIG. 10 shows a modular sorbent cartridge with two modules includingsodium chloride/sodium bicarbonate, activated carbon, ion exchangeresin, active jack bean meal (JBM)/alumina, alumina, hydrous zirconiumoxide/glass beads, and sodium chloride in the first module, which can bea reusable module, and zirconium phosphate in the second module.

FIG. 11 shows a modular sorbent cartridge with three modules includingactivated carbon, alumina, urease, and hydrous zirconium oxide in thefirst module, which can be a reusable module, zirconium phosphate in thesecond module, and zirconium phosphate and activated carbon in the thirdmodule.

FIG. 12 shows a modular sorbent cartridge with three modules includingactivated carbon in the first module, which can be a reusable module,alumina and urease in the second module, and ion-exchange resin,zirconium phosphate, and hydrous zirconium oxide in the third module,with an optional bypass line to direct fluid from the first module,which can be a reusable module, to the third module.

FIG. 13 shows a modular sorbent cartridge with three modules and with anoptional bypass line connected to another component such as a recharger.

FIG. 14 shows a modular sorbent cartridge with two modules and twoconnected bypass lines to direct flow around either module.

FIG. 15 shows a modular sorbent cartridge with two modules and a singlebypass line to direct flow around either module.

FIG. 16 shows a modular sorbent cartridge with two modules and twoseparate bypass lines to direct flow around either module.

FIG. 17 shows a modular sorbent cartridge with two modules, two bypasslines and two rechargers.

FIG. 18 shows a modular sorbent cartridge with two modules, a singlebypass line to bypass either module, or two rechargers.

FIG. 19 shows a modular sorbent cartridge with three modules, threebypass lines and three rechargers.

FIG. 20 shows a modular sorbent cartridge with two modules and twobypass lines to bypass the module, where the first module, which can bea reusable module, contains activated carbon, alumina, urease andhydrous zirconium oxide and the second module contains zirconiumphosphate.

FIG. 21 shows a modular sorbent cartridge with three modules, threebypass lines, and three rechargers, wherein the first module, which canbe a reusable module, contains activated carbon, the second modulecontains alumina and urease, and the third module contains hydrouszirconium oxide, ion-exchange resin and zirconium phosphate.

FIG. 22 shows a single module from a modular sorbent cartridge with abypass line, and two wash lines each divided into gas and fluid washlines.

FIG. 23 shows a single module from a modular sorbent cartridge with abypass line, a recharger, and two wash lines each divided into gas andfluid wash lines.

FIG. 24 shows a controlled compliant dialysis circuit utilizing asorbent cartridge.

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used hereingenerally have the same meaning as commonly understood by one ofordinary skill in the relevant art.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “an element” means one element or more thanone element.

“Blow out” refers to the process of passing a gas through a connectionline or a module.

“Bypass line” refers to a line, connected to the main line, throughwhich fluid or gas may alternatively flow.

The term “cartridge” refers to any container designed to contain apowder, liquid, or gas made for ready connection to a device ormechanism. The container can have one or more compartments. Instead ofcompartments, the container can also be comprised of a system of two ormore modules connected together to form the cartridge wherein the two ormore modules once formed can be connected to a device or mechanism.

The term “cation concentrate reservoir” refers to an object having orholding a substance that is comprised of at least one cation, forexample calcium, magnesium, or potassium ions.

The term “cation infusate source” refers to a source from which cationscan be obtained. Examples of cations include, but are not limited to,calcium, magnesium and potassium. The source can be a solutioncontaining cations or a dry composition that is hydrated by the system.The cation infusate source is not limited to cations and may optionallyinclude other substances to be infused into a dialysate or replacementfluid, non-limiting examples can be glucose, dextrose, acetic acid andcitric acid.

The term “comprising” includes, but is not limited to, whatever followsthe word “comprising.” Thus, use of the term indicates that the listedelements are required or mandatory but that other elements are optionaland may or may not be present.

A “connector” as used herein forms a fluid connection between twocomponents wherein liquid or gas can flow from one component, throughthe connector, to another component. It will be understood that theconnector provides for a fluid connection in its broadest sense and caninclude any type of tubing, fluid or gas passageway, or conduit betweenany one or more components of the invention.

The term “consisting of” includes and is limited to whatever follows thephrase “consisting of.” Thus, the phrase indicates that the limitedelements are required or mandatory and that no other elements may bepresent. The term “consisting essentially of” includes whatever followsthe term “consisting essentially of” and additional elements,structures, acts or features that do not affect the basic operation ofthe apparatus, structure or method described.

The term “container” as used herein in the context of a controlledcompliant circuit is a receptacle that may be flexible or inflexible forholding any fluid or solid, such as for example a spent dialysate fluid,or a sodium chloride or sodium bicarbonate solution or solid, or thelike.

The terms “controlled compliance” and “controlled compliant” describethe ability to actively control the transfer of fluid volume into or outof a compartment, flow path or circuit. In certain embodiments, thevariable volume of fluid in a dialysate circuit or controlled compliantflow path expands and contracts via the control of one or more pumps inconjunction with one or more reservoirs. The volume of fluid in thesystem is generally constant (unless additional fluids are added to areservoir from outside of the system) once the system is in operation ifpatient fluid volume(s), flow paths, and reservoirs are considered partof the total volume of the system (each individual volume may sometimesbe referred to as a fluid compartment). The attached reservoirs allowthe system to adjust the patient fluid volume by withdrawing fluid andstoring the desired amount in an attached control reservoir and/or byproviding purified and/or rebalanced fluids to the patient andoptionally removing waste products. The terms “controlled compliance”and “controlled compliant” are not to be confused with the term“non-compliant volume,” which simply refers to a vessel, conduit,container, flow path, conditioning flow path or cartridge that resiststhe introduction of a volume of fluid after air has been removed from adefined space such as a vessel, conduit, container, flow path,conditioning flow path or cartridge. In one embodiment, the controlledcompliant system can move fluids bi-directionally. In certain cases, thebi-directional fluid movement can be across a semi-permeable membraneeither inside or outside a dialyzer. The bi-directional fluid flow canalso occur across, through, or between vessels, conduits, containers,flow paths, conditioning flow paths or cartridges of the invention inselected modes of operation. The term “moving fluid bi-directionally” asused in connection with a barrier, such as a semi-permeable membrane,refers to the ability to move fluid across the barrier in eitherdirection. “Moving fluid bi-directionally” also can apply to the abilityto move fluid in both directions in the flow path or between a flow pathand reservoir in a controlled compliant system.

The terms “controlled compliant flow path,” “controlled compliantdialysate flow path” and “controlled compliant solution flow path” referto flow paths operating within a controlled compliant system having thecharacteristic of controlled compliance, or of being controlledcompliant as defined herein.

A “control pump” is means capable of moving fluid through a system at aspecific rate. The term “control pump,” can include for example an“ultrafiltrate pump,” which is a pump that is operable to pump fluidbi-directionally to actively control the transfer of fluid volume intoor out of a compartment or circuit.

A “control system” consists of combinations of components that acttogether to maintain a system to a desired set of performancespecifications. The control system can use processors, memory andcomputer components configured to interoperate to maintain the desiredperformance specifications. It can also include fluid or gas controlcomponents and solute control components as known within the art tomaintain the performance specifications.

A “control valve” is a valve for controlling the movement of a liquid ora gas. When the control valve directs the movement of gas, the “controlvalve” can open or close to regulate the movement of gas from a highpressure gas source to a lower pressure.

A “controller,” “control unit,” “processor,” or “microprocessor” is adevice which monitors and affects the operational conditions of a givensystem. The operational conditions are typically referred to as outputvariables of the system wherein the output variables can be affected byadjusting certain input variables.

A “degasser” is a component that is capable of removing dissolved andundissolved gasses from fluids.

The term “detachable” or “detached” relates to any component of thepresent invention that can be separated from a system, module, cartridgeor any component of the invention. “Detachable” can also refer to acomponent that can be taken out of a larger system with minimal time oreffort. In certain instances, the components can be detached withminimal time or effort, but in other instances can require additionaleffort. The detached component can be optionally reattached to thesystem, module, cartridge or other component. A detachable module canoften be part of a reusable module.

“Dialysate” is the fluid that passes through the dialyzer and does notpass through the membrane into the blood flow.

“Dialysis” is a type of filtration, or a process of selective diffusionthrough a membrane. Dialysis removes solutes of a specific range ofmolecular weights via diffusion through a membrane from a fluid to bedialyzed into a dialysate. During dialysis, a fluid to be dialyzed ispassed over a filter membrane, while dialysate is passed over the otherside of that membrane. Dissolved solutes are transported across thefilter membrane by diffusion between the fluids. The dialysate is usedto remove solutes from the fluid to be dialyzed. The dialysate can alsoprovide enrichment to the other fluid. The term “dialyzer” refers to acartridge or container with two flow paths separated by semi-permeablemembranes. One flow path is for blood and one flow path is fordialysate. The membranes can be in the form of hollow fibers, flatsheets, or spiral wound or other conventional forms known to those ofskill in the art. Membranes can be selected from the following materialsof polysulfone, polyethersulfone, poly(methyl methacrylate), modifiedcellulose, or other materials known to those skilled in the art.

“Disposable” refers to a component that is to be removed from the systemand not reused.

The term “extracorporeal,” as used herein generally means situated oroccurring outside the body.

The term “extracorporeal circuit” or “extracorporeal flow path” refersto a fluid pathway incorporating one or more components such as but notlimited to conduits, valves, pumps, fluid connection ports or sensingdevices configured therein such that the pathway conveys blood from asubject to an apparatus for hemodialysis, hemofiltration,hemodiafiltration or ultrafiltration and back to the subject.

The terms “extracorporeal flow path pump” and “blood pump” refer to adevice to move or convey fluid through an extracorporeal circuit. Thepump may be of any type suitable for pumping blood, including thoseknown to persons of skill in the art, for example peristaltic pumps,tubing pumps, diaphragm pumps, centrifugal pumps, and shuttle pumps.

“Flow” refers to the movement of a liquid or gas.

A “flow sensing apparatus” or “flow measuring apparatus” is an apparatuscapable of measuring the flow of liquid or gas within a specific area.

A “fluid” is a liquid substance.

The term “fluid communication” refers to the ability of fluid or gas tomove from one component or compartment to another within a system or thestate of being connected, such that fluid or gas can move by pressuredifferences from one portion that is connected to another portion.

The term “fluidly connectable” refers to the ability of providing forthe passage of fluid or gas from one point to another point. The twopoints can be within or between any one or more of compartments,modules, systems, components, and rechargers, all of any type.

“Infusate” is a solution of one or more salts for the adjustment of thecomposition of a dialysate.

The term “in-line” refers to a state in which a module or set of modulesis fluidly connected to a dialysis machine, dialysis flow path ordialysis circuit. Dialysis can be on-going, paused or stopped during thein-line state wherein in-line only refers to the state of the modulesbeing fluidly connected to the dialysis machine, dialysis flow path ordialysis circuit.

“Module” refers to a discreet component of a system. Each of the modulescan be fitted to each other to form a system of two or more modules.Once fitted together, the modules can be in fluid connection and resistinadvertent disconnection. A single module can represent a cartridge tobe fitted to a device or mechanism if the module is designed to containall the necessary components for an intended purpose such as a sorbentfor use in dialysis. In such a case, the module can be comprised of oneor more compartments within the module. Alternatively, two or moremodules can form a cartridge to be fitted to a device or mechanism whereeach module individually carries separate components but only whenconnected together contain in summation all the necessary components foran intended purpose such as a sorbent for use in dialysis. A module canbe referred to as a “first module,” “second module,” “third module,”etc. to refer to any number of modules. It will be understood that thedesignation of “first,” “second,” “third,” etc. does not refer to therespective placement of the module in the direction of fluid or gasflow, and merely serves to distinguish one module from another unlessotherwise indicated.

The term “non-reusable” refers to a component that cannot be reused inthe component's current state. In certain instances, the termnon-reusable can include the concept of being disposable, but is notnecessarily limited to just being disposable.

The term “off-line” refers to a state in which a module or set ofmodules is fluidly disconnected from a dialysis machine, dialysis flowpath or dialysis circuit. Dialysis can be on-going, paused or stoppedduring the off-line state wherein off-line only refers to the state ofthe modules being fluidly disconnected from the dialysis machine,dialysis flow path or dialysis circuit. The off-line state can alsoinclude a process whereby the module or set of modules is beingrecharged as defined herein.

An “operational line” or “line” is a passageway, conduit or connectorthat directs fluid or gas in a path used while the system is inoperation.

The terms “pathway,” “conveyance pathway,” “fluid flow path,” and “flowpath” refer to the route through which a fluid or gas, such as dialysateor blood travels, or the route a gas travels.

A “photocell” is a sensor capable of measuring light or otherelectromagnetic radiation.

The terms “pressure meter” and “pressure sensor” refer to a device formeasuring the pressure of a gas or liquid in a vessel or container.

A “pressure valve” is a valve wherein, if the pressure of the fluid orgas passing the valve reaches a certain level, the valve will open toallow fluid or gas to pass through.

The term “pump” refers to any device that causes the movement of fluidsor gases by the application of suction or pressure.

A “push-on fitting” is a fitting for connecting two components whereinthe components may be connected by applying pressure to the base of thefitting attached to the components.

A “quick connect fitting” is a fitting for connecting two componentswherein the male portion of the fitting contains flexible flangesextending outward with a portion on the end of the flange extendingfurther outward, and the female portion of the fitting contains aninternal ridge so that when connected, the outward extending portion ofthe flange sits under the ridge. By applying pressure, the flexibleflange can be forced inward, past the ridge, enabling easy removal.

A “recharger” is a component that is capable of recharging spent sorbentmaterial to or near its original state. A recharger may be part of thedialysis system or may be separate from the rest of the system. If therecharger is separate from the rest of the dialysis system, the term mayinclude a separate facility where the spent sorbent material is sent tobe returned to, or near, its original state. A “recharger connector” or“recharger node” is a connector that fluidly connects a recharger toanother component.

“Recharging” refers to the process of treating spent sorbent material soas to put the sorbent material back in condition for use in sorbentdialysis. Upon a sorbent material undergoing “recharging,” the sorbentmaterial can then be said to be “recharged.” The term “recyclable”refers to material that can be reused.

“Reusable” refers in one instance to a material that can be used morethan one time, possibly with treatment or recharging of the materialbetween uses. Reusable may also refer to a cartridge that contains amaterial that can be recharged by recharging the material(s) containedwithin the cartridge.

A “sensor” is a component capable of determining the states of one ormore variables in a system.

“Sorbent cartridge” refers to a cartridge that can contain one or moresorbent materials. The cartridge can be connected to a dialysis flowpath. The sorbent materials in the sorbent cartridge are used forremoving specific solutes from solution, such as urea. The sorbentcartridge can have a single compartmental design wherein all sorbentmaterials necessary for performing dialysis are contained within thesingle compartment. Alternatively, the sorbent cartridge can have amodular design wherein the sorbent materials are dispersed across atleast two different modules, which can be connected to form a unitarybody. Once the at least two modules are connected together, theconnected modules can be referred to as a sorbent cartridge, which canbe fitted to a device or mechanism. It will be understood that when asingle module contains all the sorbent materials necessary forperforming dialysis, the single module can be referred to as a sorbentcartridge.

“Sorbent materials” are materials capable of removing specific solutesfrom solution, such as urea.

“Spent dialysate” is a dialysate contacted with blood through a dialysismembrane and contains one or more impurity, or waste species, or wastesubstance, such as urea.

The term “substantially inflexible volume” refers to a three-dimensionalspace within a vessel or container that can accommodate a maximum amountof non-compressible fluid and resists the addition of any volume offluid above the maximum amount. The presence of a volume of fluid lessthan the maximum amount will fail to completely fill the vessel orcontainer. Once a substantially inflexible volume has been filled with afluid, removal of fluid from that volume will create a negative pressurethat resists fluid removal unless fluid is added and removedsimultaneously at substantially equal rates. Those skilled in the artwill recognize that a minimal amount of expansion or contraction of thevessel or container can occur in a substantially inflexible volume;however, addition or subtraction of a significant volume of fluid overthe maximum or minimum will be resisted.

“Tap water” refers to water obtained through piping from a water supplywithout additional treatment.

A “threaded fitting” is a fitting for connecting two components whereinthe male portion has a helical ridge wrapped around a cylinder, and thefemale portion is a cylindrical hole with internal helical ridges sothat when the male portion is screwed into the female portion the twocomponents are locked together.

A “twist-lock fitting” is a fitting for connecting two componentswherein the male portion of the fitting contains a head with a lengthexceeding its width, the female portion of the fitting is a hole with alength that exceeds its width and is larger than the male portion, sothat when the male portion is inserted into the female portion andeither portion is twisted the two components become locked together.

“Uremic toxins” are toxins carried in the blood supply normally removedin the kidneys.

A “valve” is a device capable of directing the flow of fluid or gas byopening, closing or obstructing one or more pathways to allow the fluidor gas to travel in a particular path. One or more valves configured toaccomplish a desired flow can be configured into a “valve assembly.”

A “wash line” is a line that directs fluid between a recharger and amodule.

The term “waste fluid” refers to any fluid that does not have a presentuse in the operation of the system. Non-limiting examples of wastefluids include ultrafiltrate, or fluid volume that has been removed froma subject undergoing a treatment, and fluids that are drained or flushedfrom a reservoir, conduit or component of the system.

The term “water source” refers to a source from which potable or notpotable water can be obtained.

The term “waste species,” “waste products,” “waste,” or “impurityspecies” refer to any molecular or ionic species originating from thepatient or subject, including metabolic wastes, molecular or ionicspecies including nitrogen or sulfur atoms, mid-weight uremic wastes andnitrogenous waste. Waste species are kept within a specific homeostasisrange by individuals with a healthy renal system.

Sorbent Dialysis

Sorbent dialysis allows dialysis with a small volume of dialysate,creating many advantages. In sorbent dialysis, spent dialysate,containing toxins removed from the blood of the patient, is passedthrough a sorbent cartridge. The sorbent cartridge of the invention cancontain sorbent materials that selectively remove specific toxins fromthe spent dialysate, either completely or by replacing them withnon-toxic material. This process converts the spent dialysate into cleandialysate, which is then redirected back to the dialyzer.

Modular sorbent cartridges, wherein each module contains select sorbentmaterials, can be useful in sorbent dialysis. This modular designcritically allows for certain portions of the sorbent cartridge to bediscarded, refilled, recycled or recharged. In certain embodiments, thesorbent materials can be structured into layers and/or intermixed. Inparticular, the modules can have the sorbent materials either intermixedor in layers wherein any combination of intermixed and layered modulescan be used interchangeably together.

To save costs and waste, the modules of the modular sorbent cartridgemay be rechargeable. The sorbent cartridges can be reusable ornon-reusable, unless specifically specified as reusable. The sorbentmaterial within the module can be recharged and made reusable by passinga solution containing the proper solutes through the layers of thesorbent module.

One non-limiting exemplary sorbent cartridge is shown in FIG. 1. Spentdialysate or fluid can flow from the bottom of the sorbent cartridge 1to the top of the cartridge. The first sorbent material the spentdialysate (or fluid) contacts can be activated carbon 2. Activatedcarbon will remove nonionic toxins from the fluid by adsorption.Creatinine, glucose, uric acid, β2-microglobulin and other non-ionictoxins, except urea, can be adsorbed onto the activated carbon, removingthose toxins from the fluid. Other non-ionic toxins will also be removedby the activated carbon. The dialysate (or fluid) then continues throughthe sorbent cartridge to the hydrous zirconium oxide layer 3. Thehydrous zirconium oxide layer 3 can remove phosphate and fluorideanions, exchanging them for acetate anions. The fluid can continue tomove through the sorbent cartridge into the alumina/urease layer 4.Urease can catalyze the reaction of urea to form ammonia and carbondioxide. The result of this is the formation of ammonium carbonate. Thephosphate anions present in the fluid can also be exchanged forhydroxide ions on the alumina. As the fluid continues through thesorbent cartridge, it reaches alumina layer 5. The alumina layer 5 canremove any remaining phosphate ions from the fluid and help retainurease within the sorbent cartridge, and in certain configurations thislayer can exchange urea for ammonium and other components. The lastlayer through which the fluid travels can be the zirconium phosphatelayer 6. In the zirconium phosphate layer 6, ammonium, calcium,potassium and magnesium cations can be exchanged for sodium and hydrogencations. Ammonium, calcium, potassium and magnesium ions allpreferentially bind to the zirconium phosphate, releasing the hydrogenand sodium ions originally present in the zirconium phosphate layer 6.The ratio of sodium to hydrogen ions released depends on the ratiooriginally present in the zirconium phosphate layer 6, and is thereforecontrollable. The result of the fluid passing through the sorbentcartridge 1 is that the fluid can be regenerated and form cleandialysate that can be safely passed back through a dialyzer to apatient. In any embodiment, potassium, calcium, and magnesium can beadded to the clean dialysate to replace any ions which were removed bythe sorbent cartridge. The ions can be added and/or controlled via aninfusate system that can be positioned on a section of the fluid flowpath after the sorbent cartridge.

Given the cost of the sorbent cartridges and sorbent materials, it wouldbe advantageous if parts of the cartridge could be reused or recharged.The present invention relates to a sorbent cartridge which includes atleast one reusable module. As shown in FIG. 2, a reusable module 11 canbe fluidly attached to a non-reusable module 12 by a connector 13 withthe use of latches 14 disposed near the circumference of the reusablemodule 11. The latches 14 can be integrally formed as part of thereusable module 11, or non-reusable module 12. Alternatively, they maybe a separate component that must be attached to the module 11. Thelatch members 14 can be mated to an annular connection ring 15 disposedon the circumference of module 12. One or more engagement members can bedisposed inside the annular connection ring 15 to engage the latches 14when positioned relative to each other using a radial motion. Suchengagement can cause a rigid connection between the reusable module 11and the non-reusable module 12. Other known locking or fasteningmechanisms known to those of ordinary skill that can effectuate rapidand effective connections between two components are contemplated by theinvention. Although only cylindrical modules are shown, it will beunderstood that modules of any shape such as rectangular, conical,triangular, etc. are contemplated by the present invention with acorrespondent fastening mechanism. In certain embodiments, the connector13 can be formed as part of the reusable module 11 and non-reusablemodule 12 and need not be a separate component that must be attached tothe module 12. Rather, the connector 13 can be molded as part of thereusable module 11 and non-reusable module 12. The connector can be acombination of female and male connectors on a module. For example, afemale connector can be disposed on one module, and a male connector onthe other to form one connector 13 (not shown). In other embodiments,the connector can be affixed by mechanical means, glued or rigidlyinterfaced to the modules 11 and 12. In any embodiment, the connector 13allows fluid to flow from the non-reusable module 12, through theconnector 13, into the reusable module 11. Alternatively, the connector13 is not a part of either the non-reusable module 12 or reusable module11 but can be a separate component such as tubing. It will be understoodthat the connector 13 is defined in its broadest sense and encompassesany fluid connection between two points.

It will be understood that different combinations of reusable andnon-reusable modules can be combined together. In certain embodiments,both modules may be reusable or both may be non-reusable. Moreover, anyone of the modules can be detachable from each other or from a casingforming the body of the sorbent cartridge. The modules can bestandardized components that are interchangeable with other modules andeasily assembled. For example, the latches 14 in FIG. 2 allow for asimple, twist-lock between two modules. The twist lock allows for themodules to be connected to each other by an easy and rapid manual motionnot requiring complex maneuvering of the modules. The connection, oncemade, can be resistant to inadvertent disengagement, but can also bereadily disengaged when desired with a similar easy and rapid manualmanipulation. For example, a force applied on the outside periphery ofthe modules near the latch, e.g. squeezing the module, can cause thelatch member 14 to disengage from the engagement members. In otherexamples. The modules can be disengaged by simply rotation the modulesrelative to each other.

In certain embodiments, each module can function as a sorbent cartridgeindependently. In other embodiments, at least two modules can cooperatetogether when engaged to each other using, for example, the latches 14in FIG. 2 and being fluidly connected together to function as a sorbentcartridge. The advantage of such a modular design as described herein isthat different sorbent materials can be dispersed between the at leasttwo modules to allow for any particular sorbent or combination ofsorbent materials to be detachable from a sorbent cartridge.

In certain embodiments, the connector 13 can be formed as part of thereusable module 11 and non-reusable module 12 and need not be a separatecomponent that must be attached to the module 12. Rather, the connector13 can be molded as part of the reusable module 11 and non-reusablemodule 12. The connector can be a combination of female and maleconnectors on a module. For example, a female connector can be disposedon one module, and a male connector on the other to form one connector13 (not shown). In other embodiments, the connector can be affixed bymechanical means, glued or rigidly interfaced to the modules 11 and 12.In any embodiment, the connector 13 allows fluid to flow from thenon-reusable module 12, through the connector 13, into the reusablemodule 11. Alternatively, the connector 13 is not a part of either thenon-reusable module 12 or reusable module 11 but can be a separatecomponent such as tubing. It will be understood that the connector 13 isdefined in its broadest sense and encompasses any fluid connectionbetween two points.

In any embodiment, one or more fluid connectors can be arranged betweenany module of the invention, and one or more such fluid connectors canbe provided in any of the described configurations herein. For example,a reusable or non-reusable module can have any number of connectors suchas 1, 2, 3, 4, 5, or more. The spacing and distribution of the fluidconnectors on the module can be positioned to enable and or increaseflow of fluid between the modules. In one example, the fluid connectorscan be spaced equidistant from each other or may be located axially orradially. The sorbent cartridge can also have one or more modules eachhaving any number of fluid connectors. In contrast to known sorbentcartridges having a unitary design in which sorbent materials arearranged in layers without any connectors between such layers, the fluidconnectors of the present invention allow for controlled fluid or gasflow to any particular sorbent or combination of sorbent materials. Thefluid connectors also allow for any particular sorbent or combination ofsorbent materials to be detachable from a sorbent cartridge. Forexample, a detachable module can be constructed with one or more sorbentmaterials. The detachable module can then be fluidly connected to thesorbent cartridge by fluid connectors. Such a configurationadvantageously allows for separate treatment, recycling, or rechargingof the sorbent or combination or mixture of sorbent materials notpossible with known sorbent cartridges. In particular, known sorbentcartridges have all the sorbent materials being formed into layers or aplurality of sorbent materials being mixed without connectors in betweensuch layers of one sorbent material, or mixtures of sorbent materials.It will be understood that the fluid connectors of the invention can becritical because the connectors control the order of sorbent materialsto which a fluid or gas is exposed, the delivery of fluid or gas to aparticular sorbent or combination of sorbent materials, and the flow andrate of flow of a fluid or gas to various sorbent materials, layers ofsorbent materials, and combination or mixtures of sorbent material.

In one aspect of the invention, it will be understood that the presentinvention contemplates at least two modules that fit together, which isdistinct from known dialysis systems having separate housings that donot form a unitary sorbent cartridge for ready attachment or insertioninto a dialysis machine. A unitary sorbent cartridge of the presentinvention contains one or more of the sorbent materials describedherein. In some embodiments, the cation and anion exchange materialsnecessarily reside in the sorbent cartridge. In other words, the cationand anion exchange resins (or other sorbent materials) are not separatedinto different housings outside a sorbent cartridge. Although theindividual sorbent materials of the present invention may be separatedinto different detachable and/or reusable modules within the singlesorbent cartridge wherein each module is connected by fluid connectors,the single sorbent cartridge design provides reduced size and weightthat is not possible with the known dialysis systems having separatehousings. The modules, as described herein, can also be further rigidlyfixed to each other by latches and engagement members or any fixing orfastening mechanism known to those of ordinary skill in the art.Notably, the sorbent cartridge of the present invention can have all ofthe sorbent materials described herein including cation and anionexchange resins within a single unitary sorbent cartridge for convenientremoval, service and monitoring. In particular, the sorbent cartridgecan have a single compartmental design wherein all sorbent materialsnecessary for performing dialysis are contained within a singlecompartment. The sorbent cartridge can also have a modular designwherein the sorbent materials are dispersed across at least twodifferent modules, which can be connected to form a unitary body. Oncethe at least two modules are connected together, the connected modulescan form a sorbent cartridge to be fitted to a device or mechanism.Advantageously, the present sorbent cartridge can therefore be easier torecycle, recharge, dispose of, service and remove from a dialysismachine. In certain embodiments, the unitary design can also provide fora compact design that can be used in a portable dialysis machine.Further, manufacturability is benefited by the unitary design.

In any embodiment, the fluid connector can be a quick-connect,twist-lock fitting, push-on fitting, or threaded fitting. Other forms ofsuch connection known to those of ordinary skill in the art are alsocontemplated by the present invention. Additionally, the connector cancomprise a length of tubing and valve or a valve assembly. In certainembodiments, the connector can be manually assembled to connect anycomponent or assembly of the invention. The connector can also be usedto rigidly connect any one of the modules to a recharger as definedherein when a separate fastening mechanism is not provided.

In any embodiment of the invention, at least one module can be in fluidcommunication with a controlled compliant dialysis circuit. Anon-limiting example of a controlled compliant dialysis circuit is shownin FIG. 24. The patient's blood is circulated through an extracorporealcircuit 370. The portion of the extracorporeal circuit 370 that containsblood drawn from the patient can be referred to as the arterial line359, which by convention is understood to mean a line for transportingblood from the patient regardless of whether blood is drawn from anartery or vein of the patient. Similarly, the portion that returns bloodto the patient can be referred to as the venous line 369. In certainembodiments, the arterial line 359 and the venous line 369 connect withone or more veins of the patient. Locomotive power for moving the bloodthrough the extracorporeal circuit 370 is provided by a blood pump 360,which is typically located along the arterial line 359. Valve 365 can beplaced on venous line 369. Blood is typically conveyed through theextracorporeal circuit 370 at a rate of 50 to 600 mL/min and can beadjusted by a controller to any required rate suitable for a procedureperformed by the invention. Blood pump 360 can be a peristaltic pump,although those skilled in the art will readily understand that othertypes of pumps can be used including diaphragm pumps, centrifugal pumps,and shuttle pumps. In certain embodiments, the blood pump 360 conveysblood through the dialyzer 356 where the blood is contacted with a bloodside of a high permeability dialysis membrane 357. Blood enters thedialyzer 356 through a blood inlet 358 and exits through a blood outlet355. The pressure of the blood prior to the blood pump 360 is measuredby a pressure meter 363 and post dialyzer 356 by a pressure meter 368.The pressure at pressure meter 363 provides an indication of theadequacy of the blood flow into the circuit where increased vacuum is anindication of a less adequate access flow. The pressure indication atpressure meter 368 can serve to detect obstructions in the venousbloodline. Additional pressure meter 353 can be located after bloodoutlet 355. An air trap 367 is placed along the extracorporeal circuit370 to prevent the introduction of air into the circulatory system ofthe patient. The air trap 367 is not limited to a particular design.Typical air traps employ a hydrophobic membrane that allows air to beseparated from an air-liquid mixture by allowing air to pass through themembrane and retaining water-based fluids. Alternatively the air trap367 can be run full, where a pressure meter can use a flexibleimpermeable membrane to transmit pressure pulses to a pressuretransducer such that there is no direct air blood interface. Air-fluiddetectors 364 and 366 are present to confirm that air is not present inthe extracorporeal circuit 370, and additional air-fluid detector 374can be present in the dialysis circuit 380. Air fluid detectors 364, 366and 374 can be ultrasonic sensors that can detect a change in solutiondensity or scattering due the presence of air or air bubbles.

During the course of conveyance of blood along the extracorporealcircuit 370, heparin or other anticoagulant is added to the blood toprevent clotting of blood within the dialyzer 356 or blood conveyancepathway/extracorporeal circuit 370. Heparin or another anticoagulant isadded from an anticoagulant container 361 at a metered rate using ananticoagulant pump 362. The anticoagulant pump 362 can be any pumpcapable of accurately metering heparin.

Dialysate within the system is conveyed through one of a first dialysatepathway 351 in the dialysate circuit, which carries dialysate to thedialyzer 356, or a second bypass pathway 381 shown in a dashed line,which serves to bypass the dialyzer 356. The dialysis circuit caninclude a pair of quick connectors 378. The first and second pathways351 and 351 have one or more conduits for conveying the dialysate.Access to the second bypass pathway 381 is controlled by valve 349. Itis understood by one skilled in the art that three-way valve 349 can bereplaced with a two-way valve or four-way valve with the same result tocontrol the flow through the dialyzer 356 or bypass pathway 381. Thefirst dialysate pathway 351, the second bypass pathway 381, and residualvolume in the dialyzer 356 including conduits for conveying thedialysate together form a dialysis circuit 380 that houses thecirculating volume of the dialysate present in the system. It isunderstood by one skilled in the art that three-way valve 349 could bereplaced with two-way valves or four-way valves with the same result tocontrol the flow through the dialyzer or bypass loop.

Dialysate that is conveyed through the dialyzer 356 on the dialysateside of the dialysis membrane 357 picks up waste products from theblood, including urea, by diffusion, hemofiltration orhemodiafiltration. Dialysate enters the dialyzer at a dialysate inletend 354 and exits at an outlet end 371. The dialysate exiting thedialyzer 356 passes through a blood leak detector 372 that can determinethe presence of blood in the dialysate indicating a breach in thedialysis membrane 357. Flow of dialysate from the dialyzer 356 can bestopped or controlled through the operation of valve 373 as well as toprevent the backup of dialysate into the dialyzer 356. The dialysate isconveyed through a sorbent cartridge 341 to remove waste products beforebeing re-conveyed through the dialyzer 356. The dialysate enters thesorbent cartridge 341 at a dialysate inlet end 340 and exits at anoutlet end 342. Refreshed dialysate exiting an outlet end 342 of thesorbent cartridge 341 can be monitored by a conductivity meter 348.Additional conductivity meter 352 can be present. Optionally, thedialysate can be filtered through a microbial filter 350. An air trap343 can be positioned before or after outlet end 342 to remove gassesintroduced into the dialysate by the sorbent cartridge 341. The volumeof actively circulating dialysate is determined by the total void volumeof the conduits and the sorbent cartridge 341 forming the dialysiscircuit 380. The void volumes of the conduits and of the sorbentcartridge 341 forming the dialysis circuit 380 have a non-expandable orsubstantially inflexible volume.

The total void volume of the conduits having a substantially inflexiblevolume prevents the passive inflow and outflow of fluid volume due topressure changes that can occur over the course of treatment. Thisresults in a benefit because not all of the pressure changes duringtreatment are under precise control by a user or operator. A controlledcompliance dialysis circuit is achieved by actively controlling theinflow (influx) and outflow (efflux) of fluid to and from the dialysiscircuit 380 and the extracorporeal circuit 370. In this manner, thevolume of fluid crossing the dialysate membrane 357 is under directcontrol and can be accurately determined.

The controlled compliance dialysis circuit can be accurately controlledto precisely remove or add fluid to the dialysis circuit. Due to thesubstantially inflexible void volume of the conduits, the sorbentcartridge 341 and other components of the dialysis circuit 380, the netmovement of fluid over any time interval across the dialysate membranecan be accurately controlled by creating a means to accurately introduceor remove fluid from the patient. This capability is used to enhance theconvective clearance of the system while controlling the net fluidremoved from the patient.

As shown in FIG. 24, the dialysate is moved along the dialysis circuit380 by a dialysate pump 379. When the control pump 375 is not operating,fluid along the length of the dialysis circuit 380 flows at a ratedetermined by the dialysate pump 379. When the control pump 375 isoperating, fluid exiting the dialyzer 356 and traveling toward theconduit 376 is flowing at a rate that is the combination of the rates ofthe control pump 375 and the dialysate pump 379. However, the fluidtraveling from the entry point of conduit 376 into the dialysis circuit380 to the dialyzer 356 is traveling at the rate of the dialysate pump379. As such, the rate of fluid traveling to the dialyzer 356 is notaffected by the operation of the control pump 375. The dialysate pumpcan be operated at a rate from about 10 to about 400 mL/min, thespecific rate being dependent on the rate of the blood pump 360 at thedesired contact time with the dialysis membrane 357 to achieve diffusionof impurities from blood to the dialysate. The rate of the dialysatepump 379 and the blood pump 360 can be controlled by a controller (notshown).

Due to the substantially inflexible void volume of the conduits and thesorbent cartridge 341, bulk fluid or water is prevented from movingacross the membrane 357 from the extracorporeal circuit 370 of thedialyzer 356 to the dialysate circuit 380 of the dialyzer 356.Specifically, due to the controlled compliant feature of the void volumeof the dialysis circuit 380, water cannot passively move from theextracorporeal side to the dialysate side through the dialysis membrane.In the event of factors that tend to increase pressure on theextracorporeal side of the dialysis membrane, such as increased bloodflow rate or blood viscosity, pressure across the membrane willautomatically be equalized due to the limited volume of the dialysiscircuit 380 and the non-compressible nature of the dialysate. In theevent of factors that tend to increase pressure on the dialysate side ofthe dialysis membrane 357, such as increased dialysis flow rate, netmovement of water from the dialysis circuit 380 to the extracorporealcircuit 370 is prevented by a vacuum that would form in the dialysatecircuit 380 in the event of such a movement. Since the dialyzer can be ahigh flux type, there is some fluid flux back and forth across thedialyzer membrane due to the pressure differential on the blood anddialysate sides of the membrane. This is a localized phenomenon due tothe low pressure required to move solution across the membrane and iscalled backfiltration, however results in no net fluid gain or loss bythe patient.

Using the controlled compliance dialysis circuit described herein, netmovement of water across the dialysis membrane occurs under activecontrol rather than passively due to pressure differences that developacross the dialysis membrane due to normal operations. A control pump375 is present and accesses the controlled compliance dialysis circuit380 through a conduit 376. In certain embodiments, the conduit 376 joinswith the controlled compliance dialysis circuit 380 at a pointdownstream from the dialyzer 356. The control pump 375 can be operatedin an influx direction that moves fluid from a control reservoir 377 tothe controlled compliance dialysis circuit 380 or in an efflux directionthat moves fluid from the controlled compliance dialysis circuit 380into the control reservoir 377. Due to the substantially inflexiblevolume of the dialysis circuit 380, volume added to the controlledcompliance dialysis circuit when the control pump 375 operates in theinflux direction causes net movement of fluid from the dialysate side ofthe dialysis membrane 357 to the extracorporeal side of the dialysismembrane 357. When the control pump 375 is operated in the effluxdirection, fluid is drawn from the extracorporeal side of the dialysismembrane 357 into the controlled compliance dialysis circuit. In certainembodiments, the control pump 375 can be operated at a rate from 0 toabout 500 mL/min in either direction.

An infusate pump 344 can be used to add a cation infusate 345 into thehemofiltration circuit 380 to generate a fluid having a properphysiological composition to serve as a replacement fluid forintroduction into the extracorporeal circuit 370. A bicarbonate solutionin a container 346 can further be added by a pump 347 to maintain aphysiological pH in the fluid prior to introduction to theextracorporeal circuit.

It will be understood that the connector provides for a fluid connectionin its broadest sense and can include any type of tubing, fluid or gaspassageway, or conduit between any one or more components of theinvention.

The sorbent material within the module can be recharged by passing asolution containing the proper solutes through the layers of the sorbentmodule. To recharge the sorbent modules in-line, the modules may beconnected by wash lines to rechargers, which contain solutions forrecharging the modules.

One embodiment of the modular sorbent cartridge is shown in FIG. 3. Thenon-reusable module 22 of the sorbent cartridge contains layers ofactivated carbon 24, alumina/urease 25, and hydrous zirconium oxide 26.The reusable module 21 contains zirconium phosphate 27. In certainembodiments, the term non-reusable can refer to the components in acartridge, and in other embodiments, the term can refer to both thecomponents in the cartridge and the cartridge itself.

After dialysis is complete, the zirconium phosphate layer 27 can containammonium, calcium, potassium and magnesium. The module 21 containing thezirconium phosphate may be removed, and the zirconium phosphaterecharged. The reusable module can be disconnected from the connectors23 connecting the reusable module to the non-reusable module, bypassline and/or wash line. The reusable module 21 is then removed from themodular sorbent cartridge. The module 21 can then be recharged,discarded and replaced, or alternatively, the sorbent material withinthe module can be removed and refilled. It will be understood that anyone of the materials used in the present invention can be used multipletimes. In such instances of multi-session use, the number of sessions inwhich one component can be used, can be the same or different from thenumber of sessions in which another component can be used. In onenon-limiting example, a module containing urease may be used two timeswhile another module containing zirconium phosphate can be used threetimes. In other cases, the module containing urease can be used threetimes, and the module containing zirconium phosphate used two times. Itwill be understood that there is no limitation on the numbers of usesfor any multi-session use module as compared to another module used inthe sorbent cartridge.

A method of recharging the zirconium phosphate module is shown in FIG.4. Wash fluid 33, containing sodium and hydrogen ions, can be passedthrough the reusable module 21, containing the used zirconium phosphate31 with bound ammonium ions. This causes an exchange of ions, whereinhydrogen and sodium ions can replace the ammonium ions on the zirconiumphosphate 31. The waste fluid 34 exiting the module 21 thus contains thefreed ammonium ions, with excess sodium and hydrogen ions. This processcreates a recharged zirconium phosphate layer 32, containing sodium andhydrogen ions for a subsequent dialysis. In certain embodiments, arecharger can be used to recharge spent sorbent material wherein therecharger contains fluid capable of restoring spent sorbent material to,or near, its original state or usable capacity.

Because calcium and magnesium ions may be more difficult to remove fromthe zirconium phosphate, and therefore the zirconium phosphate may bemore difficult to recharge, it may be advantageous to remove the calciumand magnesium in the first, non-reusable module, so that none of thoseions need to be removed in the reusable zirconium phosphate module. Suchan embodiment is in FIG. 5. Spent dialysate enters the first,non-reusable module 42 where the spent dialysate can first flow througha layer of activated carbon 44 to remove non-ionic uremic toxins. Thespent dialysate can then enter into a first layer of zirconium phosphate49. The zirconium phosphate layer 49 can remove the calcium, magnesiumand potassium from the fluid. Next the fluid can enter the hydrouszirconium oxide layer 46, which can remove the phosphate anions andexchange them with acetate anions. The fluid can then enter the ureaselayer 45 and alumina layer 48, where the urea can be converted toammonium carbonate and any remaining phosphate ions can be removed. Inother embodiments of the non-reusable module, any arrangement of theactivated carbon, zirconium phosphate, hydrous zirconium oxide layer,and urease and alumina layer is contemplated. For example, the dialysatecan first flow through a first layer of zirconium phosphate, activatedcarbon, then the hydrous zirconium oxide layer, and then enter theurease layer and alumina layer. Alternatively, the dialysate can firstflow through the hydrous zirconium oxide layer, then a first layer ofzirconium phosphate, the activated carbon, then enter the urease layerand alumina layer. Still further, the dialysate can first flow throughthe urease layer and alumina layer, then the hydrous zirconium oxidelayer, then a first layer of zirconium phosphate, and then the activatedcarbon. The fluid can then flow through the connector 43, and into thesecond, reusable, sorbent module 41. The second sorbent module 41 cancontain zirconium phosphate 47. Zirconium phosphate layer 47 canexchange the ammonium ions for sodium and hydrogen. Because the calcium,magnesium and potassium ions have already been removed by the firstzirconium phosphate layer 49, this second layer 47 will not pick upthose ions. After dialysis, the second module 41 will only containzirconium phosphate bound to ammonium ions. As such, the sorbentmaterial may be easier to recharge.

In embodiments where the reusable module contains zirconium phosphateand ion-exchange resin, or zirconium phosphate and hydrous zirconiumoxide, the module may be recharged in the same manner. The activatedcarbon layer of a reusable module may be recharged by passing a heatedwater solution through the activated carbon layer. The alumina/ureaselayers can be recharged by first passing heated water, or the solutionsdescribed above for recharging zirconium phosphate, through the layer,and then passing a solution containing urease through alumina/ureaselayers.

Another non-limiting embodiment is shown in FIG. 6. Spent dialysate canenter the first, non-reusable, module 52 where it first flows through alayer of activated carbon 54 to remove non-ionic uremic toxins. Thespent dialysate then enters into a layer of ion exchange resin 59. Theion-exchange resin layer 59 removes the calcium, magnesium and potassiumfrom the fluid. Next the spent dialysate can enter the hydrous zirconiumoxide layer 56, which removes the phosphate anions and exchanges themwith acetate anions. The spent dialysate then enters the urease layer 55and alumina layer 58, where the urea is converted to ammonium carbonateand any remaining phosphate ions are removed. In other embodiments ofthe first, non-reusable, module 52, any arrangement of the activatedcarbon, ion exchange resin, hydrous zirconium oxide layer, and ureaseand alumina layer is contemplated. For example, the dialysate can firstflow through an ion exchange resin, activated carbon, then the hydrouszirconium oxide layer, and then enter the urease layer and aluminalayer. Alternatively, the dialysate can first flow through the hydrouszirconium oxide layer, then the ion exchange resin, the activatedcarbon, then enter the urease layer and alumina layer. Still further,the dialysate can first flow through the urease layer and alumina layer,then the hydrous zirconium oxide layer, then the ion exchange resin, andthen the activated carbon. The fluid can then flow through the connector53, and into the second, reusable, sorbent module 51. The sorbent module51 contains zirconium phosphate 57. The zirconium phosphate layer 57 canexchange the ammonium ions for sodium and hydrogen. Because the calcium,magnesium and potassium ions have already been removed by theion-exchange resin layer 59, the zirconium phosphate layer 57 will notpick up those ions. Alternatively, the ion-exchange resin 59 may beselected to only remove the calcium and magnesium ions, such as by usinga chelating ion exchange resin. This will allow use of less of the ionexchange resin. If such a resin is used, the potassium will be removedby the zirconium phosphate 57. Potassium is easier to remove fromzirconium phosphate than calcium or magnesium. In other embodiments, thesorbent materials in each module may be intermixed as opposed to beingarranged in layers.

One skilled in the art will recognize that different combinations ofsorbent materials in both the reusable and non-reusable modules of thesorbent cartridge can be used without being beyond the scope of thisinvention. The sorbent materials described herein can be mixed togetherin any combination as shown in the specific embodiments of theinvention.

In any embodiment, the sorbent cartridge can be removed from a dialysissystem. The sorbent cartridge once removed can be separated into one ormore modules to be recharged, disposed of, or recycled. For example,FIG. 7 shows an embodiment wherein a second module 102 contains bothhydrous zirconium oxide and zirconium phosphate. In certain embodiments,the second module 102 can be reusable as defined herein. The spentdialysate can enter the first module 101. The spent dialysate can firstpass through an activated carbon layer 104. The spent dialysate can nextpass through a first layer of zirconium phosphate 107, which removes thepotassium, calcium and magnesium from the dialysate. Next the spentdialysate can move through the alumina/urease layer 105. In otherembodiments of the first module, any arrangement of the activatedcarbon, zirconium phosphate, and urease and alumina layer iscontemplated. For example, the fluid can first flow through activatedcarbon, then enter the urease layer, and then the zirconium phosphate.Alternatively, fluid can first flow through the zirconium phosphatelayer, then activated carbon, and then enter the urease layer andalumina layer. Still further, the fluid can first flow through theurease layer and alumina layer, then the zirconium phosphate, and thenthe activated carbon. The fluid can then pass through the connector 103,and into the second module 102. The second module 102 contains a hydrouszirconium oxide layer 106, and a second zirconium phosphate layer 108,which removes the ammonium ions from the fluid. After dialysis, thereusable module 102 containing the hydrous zirconium oxide and zirconiumphosphate can be recharged, discarded, or the sorbent material removedand new material added. In any embodiment, wash lines may be attached toconnector 103 disposed on the reusable module 102 and a second connectorpositioned after the reusable module 102 wherein the second connectorcan be positioned thereon or as part of a fluid flow path (not shown).

Another non-limiting embodiment is shown in FIG. 8. Spent dialysate canenter the first, non-reusable, module 280 where it first flows through alayer of activated carbon 283 to remove non-ionic uremic toxins otherthan urea. The spent dialysate can then enter into a layer of aluminaand urease 284, where the urea is converted to ammonium carbonate andphosphate ions are removed. Next the fluid can enter the hydrouszirconium oxide layer 285, which removes the remaining phosphate anionsand exchanges them with acetate anions. In other embodiments of thefirst module, any arrangement of the activated carbon, hydrous zirconiumoxide layer, and urease and alumina layer is contemplated. For example,the dialysate can first flow through an activated carbon layer, then thehydrous zirconium oxide layer, and then enter the urease layer andalumina layer. Alternatively, the dialysate can first flow through ahydrous zirconium oxide layer, then the activated carbon layer and thenenter the urease layer and alumina layer. Still further, the dialysatecan first flow through the urease and alumina layer, then the activatedcarbon layer, and then enter the hydrous zirconium oxide layer. Thedialysate can first flow through a hydrous zirconium oxide layer, thenthrough the alumina and urease layers, and then flow through theactivated carbon layer. Alternatively the dialysate can first flowthrough the alumina and urease layer, then through the hydrous zirconiumoxide layer, and then through the activated carbon layer. The fluid canthen flow through the connector 282, and into the second, reusable,sorbent module 281. The sorbent module 281 contains an ion exchangeresin layer 286, and a zirconium phosphate layer 287, which removes theammonium ions from the fluid. In a different embodiment of the secondmodule, the fluid can first pass through the zirconium phosphate layerand then the ion exchange resin. Alternatively, the sorbent materials ineach module may be intermixed as opposed to being arranged in layers.After dialysis, the reusable module 281 containing the zirconiumphosphate 287 and ion exchange resin 286 can be recharged, discarded, orthe sorbent material removed and new material added. Alternatively, thesorbent materials in each module may be intermixed as opposed to beingarranged in layers.

As in other embodiments, the hydrous zirconium oxide may be included ina second module as shown in FIG. 9. Spent dialysate can enter a first,non-reusable module 290 where it first flows through a layer ofactivated carbon 293 to remove non-ionic uremic toxins. The spentdialysate can then enter into a layer of alumina and urease 294, wherethe urea is converted to ammonium carbonate and phosphate ions areremoved. In another embodiment of the first, non-reusable module 290,the dialysate can first flow through the alumina and urease, and thenflow through the activated carbon. The fluid can then pass throughconnector 292 and into the second, reusable module 291. The secondmodule 291 contains a layer of hydrous zirconium oxide 295, a layer ofion exchange resin 296 and a layer of zirconium phosphate 297. In otherembodiments of the second module 291, any arrangement of the hydrouszirconium oxide, ion exchange resin and zirconium phosphate iscontemplated. For example, the fluid may first pass through a layer ofion exchange resin, then pass through a layer of hydrous zirconium oxideand then pass through the zirconium phosphate. Alternatively, the fluidmay first pass through the ion exchange resin, then pass through thezirconium phosphate and then through the hydrous zirconium oxide. Stillfurther, the fluid may pass through the zirconium phosphate, thenthrough the hydrous zirconium oxide, and then through the ion exchangeresin. In another embodiment, the fluid can first pass through thehydrous zirconium oxide layer, then through the zirconium phosphatelayer, and then through the ion exchange resin. Alternatively, the fluidcan first pass through the zirconium phosphate layer, then the ionexchange resin, and then through the hydrous zirconium oxide layer. Thesorbent materials in each module can also be intermixed as opposed tobeing arranged in layers.

Another non-limiting embodiment is shown in FIG. 10. A layer of sodiumchloride and sodium bicarbonate 304 are disposed on the first module301. The sodium chloride and sodium bicarbonate will be dissolved asliquid enters the first module 301. Spent dialysate can enter a firstmodule 301. In certain embodiments, the first module 301 can be reusableas defined herein. The spent dialysate can then enter a layer ofactivated carbon 305 to remove non-ionic uremic toxins. The spentdialysate can then enter into a layer of ion-exchange resin 306. In someembodiments, this can be a chelating ion exchange resin to selectivelyremove calcium and magnesium. The dialysate can then enter a layer ofalumina and urease 307, where the urea is converted to ammoniumcarbonate and phosphate ions are removed. In some embodiments the ureasecan be in the form of urease active jack bean meal (JBM). The spentdialysate can next enter a layer of alumina 308. The fluid can then passthrough a layer of hydrous zirconium oxide 309. In some embodiments, thehydrous zirconium oxide can be mixed with glass beads. A layer of sodiumchloride 310 can be disposed on the end of first module 301, which willbe dissolved by the fluid as it passes through the first module 301. Thefluid then passes out of the first module 301, through the connector302, and into the second module 303. In alternative embodiments of thefirst module 301, any arrangement of activated carbon, alumina, urease,ion exchange resin and hydrous zirconium oxide can be used. For example,the fluid can first pass through a layer of sodium chloride and sodiumbicarbonate, then activated carbon, then hydrous zirconium oxide, thenion-exchange resin, then alumina and urease and then the sodiumchloride. Alternatively, the fluid can first pass through a layer ofsodium chloride, then ion-exchange resin, then activated carbon, thenhydrous zirconium oxide, then alumina and urease, and then sodiumchloride. The second module can contain zirconium phosphate 311, toremove the ammonium ions from solution. In some embodiments, thezirconium phosphate 311 can be mixed with glass beads.

One skilled in the art will realize that embodiments can be includedthat involve the sorbent materials being mixed within the module, asopposed to arranging the materials in layers. Such mixing of the sorbentmaterials can be performed interspersing the sorbent materials in asingle layer by any method known to those of skill in the art. Thearrangements include not just layers of sorbent materials, but alsointermixed sorbent materials.

The modular sorbent cartridges in this invention are not limited tohaving two modules. Any number of modules may be utilized in thisinvention. A three module sorbent cartridge is shown in FIG. 11. Thefirst module 81 contains a layer of activated carbon 84, a layer ofalumina/urease 85, and a layer of hydrous zirconium oxide 86. In certainembodiments, any one of the first module 81 second module 82 or thirdmodule 83 can be reusable as defined herein. The described layers canalso be mixed together rather than being provided in layers. In otherembodiments of the first module of a three module sorbent cartridge, anyarrangement of the activated carbon, hydrous zirconium oxide layer, andurease and alumina layer is contemplated. For example, the dialysate canfirst flow through activated carbon, then the hydrous zirconium oxidelayer, and then enter the urease layer and alumina layer. Alternatively,the dialysate can first flow through the hydrous zirconium oxide layer,then the activated carbon, then enter the urease layer and aluminalayer. Still further, the dialysate can first flow through the ureaselayer and alumina layer, then the hydrous zirconium oxide layer, andthen the activated carbon. Again, the described arrangements include notjust layers, but also intermixed sorbent materials. The fluid, afterpassing through these layers, can pass through a first connector 90, andinto the second module 82. This second module 82 contains zirconiumphosphate 87. The fluid can then pass through a second connector 91, andenter a third module 83. This third module 83 contains a second layer ofzirconium phosphate 88, and a second layer of activated carbon 89 forfinal purification before passing out of the sorbent cartridge. In otherembodiments of the third module 83 of a three module sorbent cartridge,any arrangement of the activated carbon and the second layer ofzirconium phosphate are contemplated. For example, the dialysate canfirst flow through activated carbon and then the second layer ofzirconium phosphate. It will be understood that any number of modulescan be configured in the present invention. For example, a sorbentcartridge having four, five, six, seven, or more modules is contemplatedby the invention. It will be understood that the described arrangementsinclude not just layers, but also the sorbent materials beingintermixed.

As each layer of sorbent material within the modular sorbent cartridgemay be recharged, a cartridge is possible where all of the modules arereusable. It is still advantageous to utilize separate modules for thesorbent materials in order to direct the correct recharging solutionthrough the correct module, and because different sorbent materials mayneed to be replaced more often than others.

Because the ability for the zirconium phosphate layer to bind ammoniumions is finite, while the capacity of the urease layer to break downurea into ammonia is not, it is possible that the capacity of thezirconium phosphate layer may be exceeded. In such a case, excessammonium ions will be caused to pass through the sorbent cartridge andremain in the dialysate. To protect patient safety, once ammoniabreakthrough has occurred, either the dialysis session can be stopped orat least urease can be prevented from catalyzing the conversion of ureato ammonia.

FIG. 12 shows a three-module sorbent cartridge that can allow bypass ofthe alumina/urease layer in the case of ammonia breakthrough. Ammoniabreakthrough can occur when the capacity of the zirconium phosphatelayer to exchange ammonium ion is exceeded. In the event of ammoniabreakthrough, the spent dialysate can enter the first module 61, whichcontains the activated carbon layer 64. In certain embodiments, any oneof the first module 61, second module 62, or third module 63 can bereusable as defined herein. The spent dialysate then passes through afirst connector 71, and by-pass flow valve 73. In normal operation, theflow valve 73 can be set to allow the fluid to pass into the secondmodule 62. The second module 62 contains alumina/urease layer 65, whichcatalyzes the breakdown of urea into ammonium ions. In some embodiments,a single valve can be used and either first valve 73 or second valve 74can be optional. For example, valve 74 can be optional wherein thoseskilled in the art will recognize that to alternately direct flowthrough second module 62 or bypass 70 can be accomplished by aconfiguring valve 73 as a 3-way valve. Other configurations to achievethe desired alternating direct flow are contemplated by the invention.The fluid then passes through the second connector 72, by the secondvalve 74, and into the third module 63. The third module 63 can containa hydrous zirconium oxide layer 66, ion-exchange resin 68, and zirconiumphosphate layer 67. In other embodiments of the third module 63 of athree module sorbent cartridge, any arrangement of the ion-exchangeresin, hydrous zirconium oxide layer, and zirconium phosphate layer iscontemplated. For example, the dialysate can first flow throughion-exchange resin, then the hydrous zirconium oxide layer, and thenenter the zirconium phosphate layer. Alternatively, the dialysate canfirst flow through the hydrous zirconium oxide layer, then theion-exchange resin, then enter the zirconium phosphate layer. Stillfurther, the dialysate can first flow through the zirconium phosphatelayer, then the hydrous zirconium oxide layer, and then the ion-exchangeresin. Again, the described arrangements include not just layers, butalso intermixed sorbent materials. After passing through the thirdmodule, the regenerated dialysate can exit the sorbent cartridge. In theevent of ammonia breakthrough, the first valve 73 can be set to redirectthe fluid into bypass line 70. This line will cause the fluid not toenter the second module 62, and therefore the urea will not be brokendown into ammonia in the alumina/urease layer. The fluid will instead bedirected to the second valve 74, which can be optional in certainembodiments, where the fluid enters the second connector 72, and thenthe third module 63. In this way dialysis may continue, while avoidingthe creation of ammonia. In certain embodiments either the first valve73 or the second valve 74 may be optional, and those of skill in the artwill recognize that the function can be accomplished with only a singlevalve if either the first valve 73 or the second valve 74 is a 3-wayvalve. The valve or valve assembly may also include an access point fora sensor (not shown). The access point can be a portion of the valveassembly wherein a sensor can contact the fluid to take measurement datasuch as a flow or pressure reading. The form and construction of suchaccess points contemplated by the present invention are those known toone of ordinary skill in the art. In an alternative embodiment, secondvalve 74 may be removed and the cartridge may still accomplish thebypass function.

FIG. 13 shows an alternative embodiment to the sorbent cartridge shownin FIG. 12 wherein a first connector 71 and a flow valve 73 bypass flowthrough the second module 62 to a component 75. The component 75 can bea recharger used to recharge or clean the second module 62 whileattached to the sorbent cartridge. In other embodiments, the component75 can be a container storing a fluid such as a wash fluid or rechargingfluid. In still other embodiments, the component 75 can be a pump forpumping fluid. Upon passing through the component 75, fluid can returnthrough the second connector 72 via the second valve 74, which can beoptional in certain embodiments, and into the third module 63. In someembodiments, the component 75 can be removed after a period of time andfluid allowed to flow from the third module 63 through the secondconnector 72 and the second valve 74, which can be optional in certainembodiments. The component 75 can be reversibly attached and detached asnecessary. In certain embodiments either the first valve 73 or thesecond valve 74 may be optional, and those of skill in the art willrecognize that a desired flow direction and function can be accomplishedwith only a single valve if either the first valve 73 or the secondvalve 74 is a 3-way valve. To recharge the sorbent modules in-line, themodules may be connected by wash lines to rechargers, which containsolutions for recharging the modules. As different sorbent materialswill be recharging with different solutions, it is beneficial to havethe fluid bypass one or more of the modules, and to pass through one ormore of the modules.

FIG. 14 shows a configuration that may be utilized to allow fluid toselectively flow or not flow through each of the modules. Beforeentering the first module 111, the fluid can pass first valve 113. Incertain embodiments, the first module 111 can be reusable as definedherein. The first valve 113 can either direct fluid into the firstmodule 111, or into a first bypass line 117. If the fluid enters thebypass line 117, the fluid then passes to the second valve 114. Thesecond valve 114 can direct fluid either through the second bypass line118, or through the third bypass line 119 to the third valve 115, whichis in between the two modules. In some embodiments, valve 114 can beoptional wherein the bypass lines can function to move fluid around themodules. In other embodiments, valve 115 can be optional wherein thebypass lines can function to move fluid around the modules. Here, thefluid would be directed into the second module 112. Alternatively, ifthe fluid was directed through bypass line 118, then the fluid would goto fourth valve 116 and exit the portion of the system shown. Fluid thatpasses through the first module 111 also reaches third valve 115. Here,the third valve 115, which can be optional, may be set to direct fluidinto the second module 112, or alternatively through the bypass line119, which would bypass the second module 112. In this way, the valvescan be set so that fluid is directed through both modules, either one ofthe modules, or none of the modules. Alternative embodiments withdifferent valve arrangements are contemplated, for example those ofskill in the art will recognize that the same bypass functionality canbe accomplished with two valves if valves 116 and 113 are 3-way valveswithout valves 114 and 115 present.

An embodiment employing a single bypass line is shown in FIG. 15. Beforeentering the first module 271, fluid can pass through a first valve 273.In certain embodiments, the first module 271 can be reusable as definedherein. In other embodiments, the second module 272 can be reusable.First valve 273 can either direct fluid into the first module 271, orinto a bypass line 276. If the fluid enters the bypass line 276, thefluid then passes to the second valve 274, bypassing the first module271. Second valve 274 can direct fluid either through the bypass line276, or into the second module 272. If the second valve 274 directs thefluid into the bypass line 276, the fluid passes to third valve 275,bypassing the second module 272. Alternative embodiments with differentvalve arrangements are contemplated, for example those of skill in theart will recognize that the same bypass functionality can beaccomplished if valves 273 and 275 are 3-way valves without valve 274present.

Another embodiment, utilizing separate bypass lines for each module, isshown in FIG. 16. Before the fluid enters the first module 121, thefluid can pass through the first valve 123. In certain embodiments, thefirst module 121 can be reusable as defined herein. The first valve 123can be set to either direct fluid into the first module 121, or redirectthe fluid into a first bypass line 127 to second valve 124, which can beoptional After passing through the first module 121 or bypassing thefirst module 121, the fluid next passes through the third valve 125,which can be optional. This third valve 125 can be set to either directthe fluid into the second module 122, or into a second bypass line 128to the fourth valve 126. In this way the fluid can be made to flowthrough both modules, either module or none of the modules. Alternativeembodiments with different valve arrangements are contemplated, forexample those of skill in the art will recognize that the same bypassfunctionality can be accomplished if valves 126 and 123 are 3-way valveswithout valves 124 and 125 present.

In certain embodiments, the bypass lines can be formed or molded as partof the sorbent body casing. In this manner, the sorbent cartridge has aunitary body with the bypass lines being disposed thereon. One or moreof the modules can be detachable from the unitary sorbent body cartridgehaving the bypass lines molded thereon. This design avoids the need fortubing or separate lines. In other embodiments, the connectors can formthe bypass lines.

As demonstrated in FIGS. 14, 15, and 16, the precise number of valves orconnectors utilized in any embodiment may be altered without beingbeyond the scope of the invention. Valves and connectors may be added orremoved to any of the embodiments shown to accomplish the same end.Further, the functions of a four-way valve may be accomplished with twothree-way valves or three two-way valves.

The sorbent module may be connected to multiple rechargers and washlines, so that multiple layers of sorbent material may be rechargedwithout having to clean out the rechargers and lines and add new washfluid. FIG. 17 shows an embodiment utilizing multiple wash lines, bypasslines and rechargers. The first recharger 147 can be connected torecharger nodes 143 and 144. A first wash line 139 can connect the firstrecharger node 143 to a first valve 133, which is positioned before thefirst module 131. In certain embodiments, the first module 131 can bereusable as defined herein. The first valve 133 can be set to direct thefluid into the first module 131, or alternatively to bypass the firstmodule 131 through bypass line 137 which connects to a second valve 134after the first module 131, or as a third alternative to direct fluidthrough the first wash line 139 to circulate between the first module131 and the first recharger 147. The second recharger node 144 can beconnected to this second valve 134 by a second wash line 140. Fluidflowing from the first bypass line 137 or from the first module 131 canflow through the second wash line 140 to the second recharger node 144and then into the first recharger 147, or can pass to third valve 135,which can either direct the fluid into the second module 132, oralternatively to bypass the second module 132 through the second bypassline 138, which connects to the fourth valve 136 positioned after thesecond module. A third recharger node 145 can also be connected to thethird valve 135 by third wash line 141, and can connect to a secondrecharger 148. The third valve 135 can direct fluid through the thirdwash line 141 to circulate between the second module 132 and secondrecharger 148, or alternatively through the second bypass line 138, orin the alternative to the second module 132. A fourth recharger node 146can be attached by a fourth wash line 142 to the fourth valve 136. Fluidfrom the second module 132 or from the second bypass line 138 canselectively be directed through the fourth valve 136 into the fourthwash line 142 to the second recharger 148. Alternative embodiments withdifferent valve arrangements are contemplated, for example those ofskill in the art will recognize that the same bypass functionality canbe accomplished for valve 133 represented by a configuration of 2-wayvalves separately on each of first bypass line 137, first wash line 139and a connection to first module 131. Similarly, the same bypassfunctionality can be accomplished for valve 135 represented by aconfiguration of 2-way valves separately on each of second bypass line138, second wash line 139 and a connection to second module 131 withoutvalve 134 present. In an alternate embodiment, bypass lines 137 and 138,and wash lines 139 and 141 can be directly connected to the connectorsbetween the modules, rather than to valves 134 and 136, and 133 and 135,respectively.

By utilizing the rechargers and bypass lines, different recharger fluidsmay be passed through the appropriate modules. The valves may be setopen to the wash lines and closed to the connector, so that fluid isdirected to the recharger. Alternatively, the first valve 133 may be setopen to the wash line 139 and connector, while the second valve 134 isclosed to the second module 132, so that fluid is made to circulatebetween the first module 131 and the recharger 147. If the first valve133 is open to the bypass line 137, but closed to the connector, thenfluid will be directed through the bypass line 137 around the firstmodule 131. Finally, if the first valve 133 is open to the connector andthe second valve 134 and third valve 135 are open to the secondconnector, the fluid will be directed through both modules.

Another embodiment of the invention, utilizing a single bypass line, isshown in FIG. 18. The first recharger node 165 can be connected to afirst valve 153, positioned before the first module 151, by a first washline 161. In certain embodiments, the first module 151 can be reusableas defined herein. In other embodiments, the second module 152 can bereusable. A second recharger node 166 can be connected to a second valve154, positioned after the first module 151, by a second wash line 162.The first recharger node 165 and second recharger node 166 can connectthe first recharger 169. A third recharger node 167 can be connected toa third valve 155, positioned before the second module 152, by a thirdwash line 163. A fourth recharger node 168 can be connected to a fourthvalve 156, positioned after the second module 152, by a fourth wash line164. The third recharger node 167 and fourth recharger node 168 canconnect the second recharger 170. A fifth valve 158, can be positionedbefore the first module 151, and connect to a bypass line 157, whichdirects fluid around the first module 151 to a sixth valve 159,positioned between the first and second modules, 151 and 152,respectively. The bypass line 157 can be further connected to a seventhvalve 160, positioned after the second module 152. Other arrangements ofvalves are contemplated by the invention and those of skill in the artwill recognize other combinations of valves that can be employed toaccomplish these flow paths. For example, in some embodiments firstvalve 153, fourth valve 156 and sixth valve 159 can be optional and theflow path functions can be accomplished with four valves if fifth valve158, second valve 154, third valve 155 and seventh valve 160 arethree-way valves. The valves can be set to allow fluid to flow into themodules, through the bypass lines, or into the rechargers in severalcombinations.

One skilled in the art will recognize that this system is not limited tomodular sorbent cartridges having two modules. Additional modules may beutilized with additional bypass lines and rechargers. FIG. 19 shows athree-module system for in-line module recharging. A first valve 174 canbe connected to a first module 171, a first bypass line 180, and a firstwash line 183. In certain embodiments, the first module 171 can bereusable as defined herein. The first wash line 183 is connected to afirst recharger node 189. The first valve 174 may direct fluid into thefirst module 171 or into the first bypass line 180, which connects to asecond valve 175 positioned after the first module 171. The second valve175 can also be connected to a second wash line 184, and then to asecond recharger node 190. The first recharger node 189 and secondrecharger node 190 can connect the first recharger 195. The fluid thentravels to the third valve 176, positioned before the second module 172.The third valve 176 can be attached to a third wash line 185, whichconnects a third recharger node 191. This third valve 176 can directfluid into the second module 172, or into a second bypass line 181,which connects to a fourth valve 177, positioned after the second module172. This fourth valve 177 can also connect to a fourth wash line 186,which is connected to a fourth recharger node 192. The third rechargernode 191 and fourth recharger node 192 can connect the second recharger196. The fluid can then pass to a fifth valve 178, positioned before thethird module 173. The fifth valve 178 can also be attached to a fifthwash line 187, which connects to a fifth recharger node 193. The fifthvalve can direct the fluid into the third module 173, or into a thirdbypass line 182, which connects to a sixth valve 179, positioned afterthe third module 173. The sixth valve 179 can also be attached to asixth wash line 188, which connects to a sixth recharger node 194. Thefifth recharger node 193 and sixth recharger node 194 can connect thethird recharger 197. The valves can be set to allow fluid to flow intothe modules, through the bypass lines, or into the rechargers in severalcombinations. Further, additional valve arrangement known to those ofordinary skill are contemplated. In an alternate embodiment, bypasslines 180, 181 and 182, and wash lines 183, 185 and 187 can be directlyconnected to the connectors between the modules, rather than to valves175, 177 and 179, and valves 174, 176 and 178, respectively.

Various sorbent materials may be used in each of the modules of thesorbent cartridge. A non-limiting example is shown in FIG. 20. Incertain embodiments, the first module 201 can be reusable as definedherein. In other embodiments, the second module 202 can be reusable. Thefirst module 201 can contain layers of activated carbon 210,alumina/urease 211, and hydrous zirconium oxide 212. The second module202 can contain zirconium phosphate 213. After dialysis, the layers maybe recharged in each module. Fluid capable of recharging activatedcarbon, hydrous zirconium oxide, and alumina/urease may be passedthrough the first valve 203, and into the first module 201. The fluidcan then pass out of the first module 201 to second valve 205. Thisfluid may then be redirected around the second module 202 into bypassline 209. The fluid can pass to third valve 204, into third bypass line208, and to the fourth valve 206, thus bypassing the second module 202.Alternatively, fluid for recharging zirconium phosphate 213 may beintroduced. The fluid will pass to valve 203, and be redirected intobypass line 207 to third valve 204. The fluid may then be redirectedthrough bypass line 209 to the second valve 205. Here the fluid will bedirected to flow into the second module 202. This allows recharging andrecycling of either module without introducing the recharging fluid intothe other module. The sorbent materials within each module may be in anyorder. Alternatively, the sorbent materials within a module may beintermixed. Further, additional valve arrangements known to those ofordinary skill are contemplated.

Another embodiment of the invention is the 3-module cartridge shown inFIG. 21. A first valve 224 can be connected to a first module 221, afirst bypass line 230, and a first wash line 233. The wash line isconnected to a first recharger 239. The first valve 224 may direct fluidinto the first module 221 or into the first bypass line 230, which canconnect to a second valve 225 positioned after the first module 221. Thesecond valve 225 can also connect to a second wash line 234, and then tothe first recharger 239. The fluid can then travel to the third valve226, positioned before the second module 222. Third valve 226 can attachto a third wash line 235, which connects a second recharger 240. Thisthird valve 226 can direct fluid into the second module 222, or into asecond bypass line 231, which can connect to a fourth valve 227,positioned after the second module 222. The fourth valve 227 can alsoconnect to a fourth wash line 236, which is connected to the secondrecharger 240. The fluid can then pass to a fifth valve 228, positionedbefore the third module 223. The fifth valve 228 can also attach to afifth wash line 237, which connects to a third recharger 241. The fifthvalve 228 can direct the fluid into the third module 223, or into athird bypass line 232, which connects to a sixth valve 229, positionedafter the third module 223. The sixth valve 229 can also attach to asixth wash line 238, which connects to the third recharger 241. Thefirst module 221 can contain activated carbon 245. The second module 222can contain alumina/urease 246. In certain embodiments, any one of thefirst module 221, second module 222, or third module 223 can be reusableas defined herein. The third module 223 can contain hydrous zirconiumoxide 247, ion exchange resin 248, and zirconium phosphate 249. Further,additional valve arrangement known to those of ordinary skill arecontemplated. In other embodiments of the third module of a three modulesorbent cartridge, any arrangement of the ion-exchange resin, hydrouszirconium oxide layer, and zirconium phosphate layer is contemplated.For example, the dialysate can first flow through ion-exchange resin,then the hydrous zirconium oxide layer, and then enter the zirconiumphosphate layer. Alternatively, the dialysate can first flow through thehydrous zirconium oxide layer, then the ion-exchange resin, then enterthe zirconium phosphate layer. Still further, the dialysate can firstflow through the zirconium phosphate layer, then the hydrous zirconiumoxide layer, and then the ion-exchange resin. Again, the describedarrangements include not just layers, but also intermixed sorbentmaterials. After use, any of the spent modules may be discarded andreplaced. They may also be recharged. The activated carbon 245 may berecharged by passing through the first module 221 a fluid of heatedwater. The alumina/urease 246 may be recharged by first passing a fluidof heated water through second module 222, and then passing a solutioncontaining urease through. The third module 223, containing hydrouszirconium oxide 247, ion exchange resin 248, and zirconium phosphate 249may be recharged by passing through the module a solution containinghydrogen and sodium ions. By selectively directing fluid throughmodules, or through the bypass lines, each of the modules may berecharged for further use. In an alternate embodiment, bypass lines 230,231 and 232, and wash lines 233, 235 and 237 can be directly connectedto the connectors between the modules, rather than to valves 225, 227and 229, and 224, 226 and 228, respectively.

One skilled in the art will recognize that the precise order of sorbentmaterials within the modules, or the module in which a particularsorbent material is contained, may be modified without detracting fromthe invention. Various embodiments exist wherein the sorbent materialsare arranged differently within the sorbent modules. Further, thesorbent materials may be mixed within the modules, as opposed toarranging the material in layers.

In all embodiments, one or more of the modules may also be madedetachable. This will enable the detachment of one or more moduleswithout detaching the others. The detached modules can be discarded andreplaced, recharged, or the sorbent material may be discarded, themodule refilled, and then re-used. To protect against cross-usage bypatients, the detachable modules may be furnished with an identificationcomponent, such as a barcode. This will enable the same detachablemodule to be matched to a particular patient, and thereby avoid use ofthe module by another patient.

In order to ensure that all of the residual fluid is removed from thereusable modules, valves, bypass lines and wash lines, it may beadvantageous to blow a gas, such as air, or an inert gas such as argon,through the module. In alternative embodiments, the gas may be air,filtered air, nitrogen, helium, or other gas. The wash line may beadapted so that a gas may be blown through the module instead of, or inaddition to, a wash liquid.

Alternatively, a wash line may be divided into two lines as shown inFIG. 22. FIG. 22 shows a first module 251 from an embodiment similar tothat shown in FIG. 17, wherein the wash line is adapted to utilize botha liquid and a gas. In certain embodiments, the first module 251 can bereusable as defined herein. The first wash line 255 can connect to afirst valve 252 positioned before the first module 251. The first valve252 can also connect to the first bypass line 254. The first bypass line254 can direct either liquid or gas around the first module 251 to thesecond valve 253. The first wash line 255 can be further divided intotwo lines. These lines are the liquid wash line 257, and the gas washline 258. A second wash line 256 can connect to the second valve 253,and also have both a liquid wash line 259 and a gas wash line 260. Thisembodiment allows both gas and liquid to pass either into the firstmodule, or into the bypass line and around the first module. A secondmodule, second bypass line, and third and fourth fluid lines areattached, so that fluid or gas may selectively be made to enter eithermodule, or to bypass them.

FIG. 23 shows an alternative embodiment utilizing both a gas and liquidline. The first wash line 326 can connect a first valve 324 to a secondvalve 322. The first valve 324 can be connected to the rechargerconnector 329, and a fluid collector 331. The recharger connector 329can also be attached to third valve 325. Third valve 325 can connect thegas source 330 and fourth valve 323 via second wash line 327. Both thesecond valve 322 and the fourth valve 323 connect to the module 321 anda bypass line 328. This embodiment allows both gas and liquid tocirculate through the module 321, or around the module.

In addition to dividing the wash line into a gas wash line and a liquidwash line, the wash line may be divided into two different liquid lines.This enables different liquids to travel between the recharger and themodules.

To make use of the modular sorbent cartridge easier, the valve or valveassembly may be operated by a programmable controller or computer systemthat can be programmed to regulate flow through the valves and into andout of the modules. An optical sensor, photocell or other flow sensingapparatus may detect the flow of fluid through any two points in thesorbent cartridge. For example, an optical fluid flow device can beprovided for measuring flow wherein the device includes an optical fluidpressure measuring device having sensors positioned in any one of theflow paths between the modules, in the connectors, or in the valveassemblies. Preferably, the sensors will be placed in a passagewaydefined between the modules. In certain embodiments, the optical fluidsensors can be connected to an interferometer associated with anopto-electronic demodulator which has an output signal representing thedifferential pressure between the two sensed areas. In otherembodiments, a flow sensing apparatus can have a flow-responsive elementprojecting into a fluid flow path, and a position sensor associated withthe element which detects a change in position of the flow responsiveelement in response to the fluid flow. The flow-responsive element canbe made of a wide variety of materials having the desired propertiesknown to those of ordinary skill in the art.

It will be apparent to one skilled in the art that various combinationsand/or modifications and variations can be made in the dialysis systemdepending upon the specific needs for operation. Moreover, featuresillustrated or described as being part of one embodiment may be used onanother embodiment to yield a still further embodiment.

What is claimed is:
 1. A sorbent cartridge, comprising: at least onereusable module wherein the reusable module contains at least onematerial that can be recharged by recharging the at least one materialcontained within the reusable module, the reusable module having one ormore connectors fluidly connectable to any part of a fluid flow pathselected from any one of a wash line, a bypass line, and the fluid line;wherein the wash line is fluidly connectable to a recharger; wherein thebypass line is fluidly connectable to another module to bypass thereusable module; and wherein the fluid line is fluidly connectable toany portion of a dialysis circuit, wherein the reusable module and asecond module are connected in series, wherein the reusable module isfluidly connected to a first set of one or more valves positioned on afirst set of one or more connectors before the reusable module, whereinfluid is directed into the reusable module, and wherein the bypass lineis fluidly connected to the first set of one or more valves such thatfluid can bypass the reusable module; wherein a first recharger isfluidly connected to the first set of one or more valves such that fluidmay be directed from the first recharger to the reusable module; whereinthe reusable module is fluidly connected to a second set of one or morevalves positioned on a second set of one or more connectors after thereusable module and before the second module, such that fluid may bedirected from the reusable module into the second module; wherein thebypass line is fluidly connected to the second set of one or more valvessuch that fluid can bypass the second module; wherein the firstrecharger is connected to the second set of one or more valves such thatfluid may be directed from the reusable module to the first recharger;wherein a second recharger is fluidly connected to the second set of oneor more valves such that fluid may be directed from the second rechargerto the second module; and wherein the second recharger is fluidlyconnected to a third set of one or more connectors positioned after thesecond module such that fluid may be directed from the second module tothe second recharger.
 2. The sorbent cartridge of claim 1, furthercomprising at least one valve positioned before and/or after the atleast one reusable module on the connectors to selectively direct flowthrough the at least one reusable module, the wash line, the recharger,and the bypass line.
 3. The sorbent cartridge of claim 2, furthercomprising any one of a four-way, three-way, two-way valve, orcombinations thereof, positioned at least one of before and after thereusable module on the connectors to selectively direct fluid flowthrough at least one of the reusable module, the wash line, therecharger and/or the bypass line.
 4. The sorbent cartridge of claim 3,wherein a bypass line connects a first valve positioned on a connectorbefore the reusable module to a second valve positioned on a connectorbetween the reusable and second module, and connects the second valve toa third valve positioned on a connector after the second module.
 5. Thesorbent cartridge of claim 2, wherein the at least one valve is operatedunder control of a programmable controller or computer system toregulate flow into, out of, and between the modules.
 6. The sorbentcartridge of claim 2, wherein fluid flow through the at least one valveis sensed by a photocell or other flow sensing and/or measuringapparatus.
 7. The sorbent cartridge of claim 1, wherein the reusablemodule is configured to be in an off-line state by being fluidlyconnectable to the recharger.
 8. The sorbent cartridge of claim 1,wherein the reusable module is configured to be in an in-line state bybeing fluidly connectable to any one of the fluid line and the bypassline.
 9. The sorbent cartridge of claim 1, wherein a first bypass lineconnects a first valve positioned on a connector before the reusablemodule to a second valve; a second bypass line connects the second valveto a third valve positioned on a connector between the first and secondmodule; and a third bypass line connects the second valve to a fourthvalve positioned on a connector after the second module.
 10. The sorbentcartridge of claim 1, wherein a first bypass line connects a first valvepositioned on a connector before the reusable module to a second valvepositioned on a connector between the reusable module and the secondmodule; and a second bypass line connects a third valve positioned onthe connector between the reusable module and the second module to afourth valve positioned on a connector after the second module.
 11. Thesorbent cartridge of claim 1, wherein a first bypass line connects afirst valve positioned on a connector before the reusable module to asecond valve positioned on a connector between the reusable and secondmodules; a second bypass line connects a third valve positioned on theconnector between the reusable module and second module to a fourthvalve positioned on a connector after the second module; a first washline connects the first valve to a first recharger connector; a secondwash line connects the second valve to a second recharger connector; athird wash line connects the third valve to a third recharger connector;and a fourth wash line connects the fourth valve to a fourth rechargerconnector.
 12. The sorbent cartridge of claim 1, wherein a first valvepositioned on a connector before the reusable module connects a firstwash line to a first recharger connector; a second valve positioned on aconnector between the reusable module and second module connects asecond wash line to a second recharger connector; a third valvepositioned on the connector between the first and second modulesconnects a third wash line to a third recharger connector; a fourthvalve positioned on a connector after the second module connects afourth wash line to a fourth recharger connector; a fifth valvepositioned on the connector before the reusable module connects a bypassline to a sixth valve positioned on the connector between the reusablemodule and second module, and further connects to a seventh valvepositioned on the connector after the second module.
 13. The sorbentcartridge of claim 1, comprising at least one reusable removable modulehaving one or more connectors.
 14. The sorbent cartridge of claim 13,wherein the at least one reusable module contains sorbent material. 15.The sorbent cartridge of claim 14, wherein the sorbent material isselected from a group consisting of zirconium phosphate, hydrouszirconium oxide, activated carbon, alumina, urease and ion exchangeresin.
 16. The sorbent cartridge of claim 13, wherein the at least onereusable module contains multiple sorbent materials.
 17. The sorbentcartridge of claim 16, wherein the multiple sorbent materials are mixedtogether.
 18. The sorbent cartridge of claim 13, wherein the reusablemodule is recyclable.
 19. The sorbent cartridge of claim 1, wherein thecartridge comprises at least one non-reusable module.
 20. The sorbentcartridge of claim 19, wherein the at least one non-reusable modulecontains sorbent material.
 21. The sorbent cartridge of claim 20,wherein the sorbent material is selected from a group consisting ofzirconium phosphate, hydrous zirconium oxide, activated carbon, alumina,urease and ion exchange resin.
 22. The sorbent cartridge of claim 19,wherein the at least one non-reusable module contains multiple sorbentmaterials.
 23. The sorbent cartridge of claim 1, wherein the one or moreconnectors connecting the modules are selected from a group consistingof quick-connect, twist-lock, push-on, and threaded fittings.
 24. Thesorbent cartridge of claim 1, wherein the one or more connectorscomprise a length of tubing and a valve or valve assembly.
 25. Thesorbent cartridge of claim 1, wherein the at least one reusable moduleis detachable from the sorbent cartridge.
 26. The sorbent cartridge ofclaim 1, wherein the at least one reusable module has a barcode or otheridentification system.
 27. The sorbent cartridge of claim 1, wherein theconnectors include an access point for a sensor.
 28. The sorbentcartridge of claim 1, wherein the at least one reusable module and theother module are part of a controlled compliant dialysis circuit havinga generally constant volume of fluid during operation.
 29. The sorbentcartridge of claim 1, further comprising a control pump for circulatingfluid in the fluid flow path.
 30. The sorbent cartridge of claim 1,wherein the bypass line is fluidly connected to the first set of one ormore valves such that fluid can bypass the reusable module; wherein thereusable module and the bypass line are fluidly connected to a secondset of one or more valves positioned on a second set of one or moreconnectors after the reusable module and before the second module, suchthat fluid is directed from the first module into the second module; andwherein the bypass line is fluidly connected to the second set of one ormore valves such that fluid can bypass the second module.
 31. Thesorbent cartridge of claim 1, wherein the at least one reusable moduleis connected to the bypass line, the wash line, and the fluid line ofthe dialysis circuit through one or more valves.
 32. The sorbentcartridge of claim 31, wherein the one or more valves open to one of thebypass line, the wash line, and the fluid line and close to another oneof the bypass line, the wash line, and the fluid line.
 33. A sorbentcartridge, comprising: at least one reusable module wherein the reusablemodule contains at least one material that can be recharged byrecharging the at least one material contained within the reusablemodule, the reusable module having one or more connectors fluidlyconnectable to any part of a fluid flow path selected from any one of awash line, a bypass line, and the fluid line; wherein the wash line isfluidly connectable to a recharger; wherein the bypass line is fluidlyconnectable to another module to bypass the reusable module; and whereinthe fluid line is fluidly connectable to any portion of a dialysiscircuit, wherein the reusable module, a second module, and a thirdmodule are connected in series, wherein the reusable module is fluidlyconnected to a first set of one or more valves positioned on a first setof one or more connectors before the reusable module, such that fluidmay be directed into the reusable module, and wherein the bypass line isfluidly connected to the first set of one or more valves such that fluidcan bypass the reusable module; wherein a first recharger is fluidlyconnected to the first set of one or more valves such that fluid may bedirected from the first recharger to the reusable module; wherein thereusable module is fluidly connected to a second set of one or morevalves positioned on a second set of one or more connectors after thereusable module and before the second module, such that fluid may bedirected from the reusable module into the second module; wherein thefirst recharger is connected to the second set of one or more valvessuch that fluid is directed from the reusable module to the firstrecharger; wherein the bypass line is fluidly connected to the secondset of one or more valves such that fluid can bypass the second module;wherein a second recharger is fluidly connected to the second set of oneor more valves such that fluid may be directed from the second rechargerto the second module; wherein the second module is fluidly connected toa third set of one or more valves positioned on a third set of one ormore connectors after the second module and before the third module,such that fluid may be directed from the second module into the thirdmodule; wherein the second recharger is fluidly connected to the thirdset of one or more valves such that fluid from the second module may bedirected to the second recharger; wherein the bypass line is fluidlyconnected to the third set of one or more valves such that fluid canbypass the third module; wherein a third recharger is fluidly connectedto the third set of one or more valves such that fluid may be directedfrom the third recharger to the third module; wherein the third moduleis fluidly connected to a fourth set of one or more connectors; andwherein the third recharger is fluidly connected to the fourth set ofone or more connectors such that fluid may be directed from the thirdmodule to the third recharger.
 34. The sorbent cartridge of claim 33,wherein the reusable module contains urease, the second module containszirconium phosphate and the third module contains zirconium oxide. 35.The sorbent cartridge of claim 34, wherein the reusable module furthercontains activated carbon.
 36. The sorbent cartridge of claim 35,wherein the reusable module contains a first layer of activated carbon,a second layer of urease downstream of the first layer, and a thirdlayer of activated carbon downstream of the second layer.